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FAT
Developer Microsoft
Full Name File Allocation Table
(12-bit version) (16-bit version) (32-bit version)
Introduced before 1980 (Microsoft Disk BASIC) November 1987, (Compaq DOS 3.31) August 1996 (Windows 95 OSR2)
Partition identifier 0x01 (MBR) 0x04, 0x06, 0x0E (MBR) 0x0B, 0x0C (MBR)
EBD0A0A2-B9E5-4433
-87C0-68B6B72699C7
(GPT)
Structures
Directory contents Table
File allocation Linked List
Bad blocks Cluster tagging
Limits
Max file size 4 GB minus 1 byte (or block size if smaller)
Max cluster count 4,077 (212-19) 65,517 (216-19) 268,435,437 (228-19)
Max filename size 8.3 filename, or 255 UTF-16 characters when using LFN
Max volume size 32 MB 2 GB
4 GB with 64KB clusters (not widely supported)
2 TB
8 TB (with 32KB clusters)
16 TB (with 64KB clusters, not widely supported)
Features
Dates recorded Creation, modified, access (accuracy to day only)
(Creation time and access date are only available when ACCDATE support is enabled)
Date range January 1, 1980 - December 31, 2107
Date resolution 2 s
Forks Not natively
Attributes Read-only, hidden, system, volume label, subdirectory, archive, (NetWare only) executable
Permissions Global/directory/file-based only with DR-DOS and Multiuser DOS, world/group/owner file permissions only with multiuser security No
Transparent compression Per-volume, Stacker, DoubleSpace, DriveSpace No
Transparent encryption Per-volume only with DR-DOS No
.File Allocation Table or FAT is a computer file system architecture now widely used on many computer systems and most memory cards, such as those used with digital cameras.^ File Allocation Table FAT structure .
  • File Allocation Table FAT DBR hard drives operating systems FAT32 file systems 15 January 2010 7:15 UTC www.p-dd.com [Source type: Reference]

^ Most laptop computers have a socket that hosts PCMCIA memory cards.
  • Mass Memory Interface for removable storage and file transfer 15 January 2010 7:15 UTC www.mosaic-industries.com [Source type: Reference]

^ All files are allocated space in clusters of sectors using a file allocation table (FAT).
  • Hard Drive Clusters and File Allocation 15 January 2010 7:15 UTC www.dewassoc.com [Source type: Reference]

.FAT file systems are commonly found on floppy disks, flash memory cards, digital cameras, and many other portable devices because of its relative simplicity.^ The file system on the floppy disk need not be one that was defragmented recently.
  • Systech Software - Floppy disk recovery, Hard disk recovery - Editor's Choice utilities 15 January 2010 7:15 UTC www.bestdiskrecovery.com [Source type: Reference]

^ Microsoft opens FAT file system .
  • file allocation table stories - ZDNet Asia 15 January 2010 7:15 UTC www.zdnetasia.com [Source type: General]

^ File systems 101: FAT .
  • file allocation table stories - ZDNet Asia 15 January 2010 7:15 UTC www.zdnetasia.com [Source type: General]

.Performance of FAT compares poorly to most other file systems as it uses overly simplistic data structures, making file operations time-consuming, and makes poor use of disk space in situations where many small files are present.^ That File System guarantees the data consistency.
  • Shared File Systems 15 January 2010 7:15 UTC www.communigate.com [Source type: Reference]
  • CommuniGate Pro: Cluster Storage 15 January 2010 7:15 UTC www.communigate.com [Source type: Reference]

^ Efficient use of disk space.
  • MAC file systems overview 15 January 2010 7:15 UTC www.vitaldata.ca [Source type: Reference]

^ Can I recover deleted files from the disk formatted using FAT32 file system?
  • Pandora File Recovery support page. Recover deleted files of any type - free. 15 January 2010 7:15 UTC www.pandorarecovery.com [Source type: Reference]

.For floppy disks, the FAT has been standardized as ECMA-107[1] and ISO/IEC 9293.[2][3] Those standards include only FAT12 and FAT16 without long filename support; long filenames with FAT is partially patented.^ Long filename support .
  • File Allocation Table - Waikato Linux Users Group 15 January 2010 7:15 UTC test.wlug.org.nz [Source type: FILTERED WITH BAYES]

^ FAT16 and FAT12 partitions ONLY. (FAT12 file system includes floppies).
  • RECOVER Fixed/Floppy Disk v3.0 Release 3 and RECOVER Fixed/Floppy Disk v2.2 - Technical Support Page 15 January 2010 7:15 UTC www.bestdiskrecovery.com [Source type: Reference]

^ Until recently, the most frequently used file system for personal computers and workstations has been the FAT family of file systems, consisting of FAT12, FAT16, VFAT and FAT32.
  • Hard Drive Clusters and File Allocation 15 January 2010 7:15 UTC www.dewassoc.com [Source type: Reference]

.The FAT file system is relatively straightforward technically and is supported by virtually all existing operating systems for personal computers.^ Mac OS X operating system supports many file system.
  • MAC file systems overview 15 January 2010 7:15 UTC www.vitaldata.ca [Source type: Reference]

^ NTFS file system supports file compression.
  • Untitled Document 15 January 2010 7:15 UTC www.lc-tech.com [Source type: Reference]

^ All JFS2 file systems support large files.
  • System Management Concepts:Operating System and Devices - File System Types 15 January 2010 7:15 UTC moka.ccr.jussieu.fr [Source type: Reference]

.This makes it a useful format for solid-state memory cards and a convenient way to share data between operating systems.^ This ubiquity makes it an ideal format for floppy disks and solid-state memory cards, and a convenient way of sharing data between disparate operating systems installed on the same computer (a multiboot environment).
  • Hi foxb! what is FAT/FAT32 file system? - Yahoo! Answers 15 January 2010 7:15 UTC answers.yahoo.com [Source type: General]

^ RT025 Operating system data error.

^ In what operating systems NTFS is used?
  • Pandora File Recovery support page. Recover deleted files of any type - free. 15 January 2010 7:15 UTC www.pandorarecovery.com [Source type: Reference]

Contents

History

.The FAT file system was developed by Bill Gates and Marc McDonald during 1976–1977.[4][5] It was the primary file system for various operating systems including DR-DOS, FreeDOS, MS-DOS, OS/2 (v1.1) and Microsoft Windows (up until Windows Me).^ Microsoft Windows is a family of operating systems by Microsoft.
  • File extension MFT - NTFS master file table file 15 January 2010 7:15 UTC www.file-extensions.org [Source type: Reference]

^ Mac OS X operating system supports many file system.
  • MAC file systems overview 15 January 2010 7:15 UTC www.vitaldata.ca [Source type: Reference]

^ First up: the FAT file system and ClearType fonts .
  • file allocation table stories - ZDNet Asia 15 January 2010 7:15 UTC www.zdnetasia.com [Source type: General]

.The FAT file system was created for managing disks in Microsoft Standalone Disk BASIC.^ Standalone file system .
  • File Allocation Methods - SAM-QFS Documentation - wikis.sun.com 15 January 2010 7:15 UTC wikis.sun.com [Source type: Reference]

^ The system comprises a FEProm manager and a file system.
  • Method and system for file system management using a flash-erasable, programmable, read-only memory - Patent 6256642 15 January 2010 7:15 UTC www.freepatentsonline.com [Source type: Reference]

^ The type of the file system is FAT. .
  • Troubleshooting Tools and Strategies 15 January 2010 7:15 UTC technet.microsoft.com [Source type: Reference]

.In August 1980 Tim Paterson incorporated FAT into his 86-DOS operating system for the S-100 8086 CPU boards;[6] the file system was the main difference between 86-DOS and its predecessor, CP/M.^ The type of the file system is FAT. .
  • Troubleshooting Tools and Strategies 15 January 2010 7:15 UTC technet.microsoft.com [Source type: Reference]

^ What is the difference between FAT,FAT32 & NTFS file system?
  • What is the difference between FAT,FAT32 & NTFS file system? - Yahoo! Answers 15 January 2010 7:15 UTC answers.yahoo.com [Source type: General]

^ This Free scan will fix your PC automatically www.errorfix.com Related Topics NTFs File System UNIX File System Fat32 File System File Management System Windows File Systems Distributed File System Raw File System File System in LINUX XFs NTFs Vs Fat Internet Difference between Fat Fat32 .
  • Questions about Fat File System - Ask.com 15 January 2010 7:15 UTC www.ask.com [Source type: Reference]

.The name originates from the usage of a table which centralizes the information about which areas belong to files, are free or possibly unusable, and where each file is stored on the disk.^ Oracle stores information in memory and on disk.

^ File Data Area Stores the file data.
  • Denali Software, Inc.: Spectra™ NAND Flash File System 15 January 2010 7:15 UTC www.denali.com [Source type: Reference]

^ This is a Directory Table that stores information about the files and directories in the root directory.
  • - FAT12, FAT16 and FAT32 Windows File System 15 January 2010 7:15 UTC www.dataraid.com [Source type: Reference]

.To limit the size of the table, disk space is allocated to files in contiguous groups of hardware sectors called clusters.^ The TFAT file system then finds and allocates a new cluster on disk.
  • Transaction-safe FAT file system - Patent 7174420 15 January 2010 7:15 UTC www.freepatentsonline.com [Source type: Reference]

^ In FAT32 file allocation table is flexible and depends on cluster size (and therefore, number of clusters).
  • Nokia Support Discussions - Re: Help! N95 RAM going very low on many files on microSD card - Nseries Devices and S60 Smartphones - Nokia Support Discussions 15 January 2010 7:15 UTC discussions.europe.nokia.com [Source type: General]
  • Nokia Support Discussions - Help! N95 RAM going very low on many files on microSD card - Nseries Devices and S60 Smartphones - Nokia Support Discussions 15 January 2010 7:15 UTC discussions.europe.nokia.com [Source type: General]

^ Extent Allocation A disk space allocation method in which extents of variable size are allocated to a file.
  • Scalability and Performance in Modern Filesystems 15 January 2010 7:15 UTC oss.sgi.com [Source type: Reference]

.As disk drives have evolved, the maximum number of clusters has dramatically increased, and so the number of bits used to identify each cluster has grown.^ NTFS uses 64-bit cluster numbers.
  • Spotmau Support Web Site » Windows File System Formats 15 January 2010 7:15 UTC www.spotmausupport.com [Source type: Reference]

^ The name of each FAT format includes a number that indicates the number of bits the format uses to identify clusters on a disk.
  • Spotmau Support Web Site » Windows File System Formats 15 January 2010 7:15 UTC www.spotmausupport.com [Source type: Reference]

^ The fact that they are marked as bad means that the system prevents the disk from using them, so previously identified bad sectors pose no danger to your data.
  • Troubleshooting Tools and Strategies 15 January 2010 7:15 UTC technet.microsoft.com [Source type: Reference]

.The successive major versions of the FAT format are named after the number of table element bits: 12, 16, and 32. The FAT standard has also been expanded in other ways while preserving backward compatibility with existing software.^ Starting cluster number in the file allocation table (16 bits).

^ On FAT 16 and FAT 32 systems, the table is on the disk's outermost track.
  • Clusters, Sectors & Tables - Review Tom's Hardware : The WinFS File System For Windows Longhorn: Faster & Smarter 15 January 2010 7:15 UTC www.tomshardware.com [Source type: General]

^ NO WAY with FAT-32!
  • Slashdot Ask Slashdot Story | Best Filesystem For External Back-Up Drives? 15 January 2010 7:15 UTC ask.slashdot.org [Source type: General]

FAT12

.The initial version of FAT is now referred to as FAT12.^ This initial version of FAT is now referred to as FAT12 .
  • - FAT12, FAT16 and FAT32 Windows File System 15 January 2010 7:15 UTC www.dataraid.com [Source type: Reference]

^ FAT refers to volumes formatted with FAT12, FAT16, or FAT32.
  • Troubleshooting Tools and Strategies 15 January 2010 7:15 UTC technet.microsoft.com [Source type: Reference]

.Designed as a file system for floppy disks, it limited cluster addresses to 12-bit values, which not only limited the cluster count to 4078,[7] but made FAT manipulation tricky with the PC's 8-bit and 16-bit registers.^ The TFAT file system then finds and allocates a new cluster on disk.
  • Transaction-safe FAT file system - Patent 7174420 15 January 2010 7:15 UTC www.freepatentsonline.com [Source type: Reference]

^ RT030 File system is read only.

^ Starting cluster number in the file allocation table (16 bits).

.(Under Linux, FAT12 is limited to 4084 clusters.^ FAT12’s 12-bit cluster identifier limits a partition to storing a maximum of 212 (4096) clusters.
  • Spotmau Support Web Site » Windows File System Formats 15 January 2010 7:15 UTC www.spotmausupport.com [Source type: Reference]

[8]) .The disk's size is stored as a 16-bit count of sectors, which limited the size to 32 MB.^ File size (32 bits).

^ The disk addresses are 32 bits in size.
  • General Programming Concepts: Writing and Debugging Programs - JFS File Space Allocation 15 January 2010 7:15 UTC www.ncsa.illinois.edu [Source type: Reference]

^ Also, file sizes are limited to 16 terabytes.

[9] .FAT12 was used by several manufacturers with different physical formats, but a typical floppy disk at the time was 5.25-inch, single-sided, 40 tracks, with 8 sectors per track, resulting in a capacity of 160 KB for both the system areas and files.^ For example, the standard format for 8-inch single-density disks uses four 128-byte sectors per allocation unit.

^ Can I recover deleted files from the disk formatted using FAT32 file system?
  • Pandora File Recovery support page. Recover deleted files of any type - free. 15 January 2010 7:15 UTC www.pandorarecovery.com [Source type: Reference]

^ Remember that the first sector ( sector 1 on track 0, side 0 ) on a floppy disk is the Boot Sector.
  • RECOVER Fixed/Floppy Disk v3.0 Release 3 and RECOVER Fixed/Floppy Disk v2.2 - Technical Support Page 15 January 2010 7:15 UTC www.bestdiskrecovery.com [Source type: Reference]

The FAT12 limitations exceeded this capacity by a factor of ten or more.
.By convention, all the control structures were organized to fit inside the first track, thus avoiding head movement during read and write operations, although this varied depending on the manufacturer and physical format of the disk.^ All the disks work with are blocks, and all they can do is read and write those blocks.

^ The read/write heads of the disk drive ski in the air to get to the next sector or track.
  • RECOVER Fixed/Floppy Disk v3.0 Release 3 and RECOVER Fixed/Floppy Disk v2.2 - Technical Support Page 15 January 2010 7:15 UTC www.bestdiskrecovery.com [Source type: Reference]

^ An entry-level diskette at the time would be 5.25", single-sided, 40 tracks , with 8 sectors per track, resulting in a capacity of slightly less than 160KB. The above limits exceeded this capacity by one or more orders of magnitude and at the same time allowed to fit all the control structures inside the first track, thus avoiding head movement during read and write operations.
  • - FAT12, FAT16 and FAT32 Windows File System 15 January 2010 7:15 UTC www.dataraid.com [Source type: Reference]

.At the time FAT12 was introduced, DOS did not support hierarchical directories, and the maximum number of files was typically limited to a few dozen.^ A directory within a directory in a hierarchical file system.
  • http://www.redhat.com/docs/glossary/index.html 15 January 2010 7:15 UTC www.redhat.com [Source type: Reference]

^ Maximum number of files in the root directory (FAT12/16; 0 for FAT32) .
  • The FAT File System 15 January 2010 7:15 UTC www.c-jump.com [Source type: Reference]

^ This time, I’m going to discuss the limits on the maximum number of threads and processes supported on Windows.
  • Mark's Blog 15 January 2010 7:15 UTC blogs.technet.com [Source type: FILTERED WITH BAYES]

Hierarchical directories were introduced in MS-DOS version 2.0.[10]
.A limitation which was not addressed until much later was that any bad sector in the control structures area, track 0, could prevent the disk from being usable.^ A track is a circular area of the disk surface.
  • RECOVER Fixed/Floppy Disk v3.0 Release 3 and RECOVER Fixed/Floppy Disk v2.2 - Technical Support Page 15 January 2010 7:15 UTC www.bestdiskrecovery.com [Source type: Reference]

^ The fact that they are marked as bad means that the system prevents the disk from using them, so previously identified bad sectors pose no danger to your data.
  • Troubleshooting Tools and Strategies 15 January 2010 7:15 UTC technet.microsoft.com [Source type: Reference]

^ To provide maximum usable data space on the disk, both internal fragmentation and FAT size must be considered because both consume data area.

.The DOS formatting tool rejected such disks completely.^ One such file system was developed by Microsoft Corporation for its Disk Operating System (MS-DOS).
  • Method and system for file system management using a flash-erasable, programmable, read-only memory - Patent 6256642 15 January 2010 7:15 UTC www.freepatentsonline.com [Source type: Reference]

^ Once a SCSI disk format has completed successfully, other problems may appear over time.

^ Completely Automated Disk level data recovery software for Floppy Disks recovers files from inaccessible and need-to-be-formatted floppy disks.
  • Damaged File Allocation Table downloads at VicMan 15 January 2010 7:15 UTC www.vicman.net [Source type: Reference]

.Bad sectors were allowed only in the file area, where they made the entire holding cluster unusable as well.^ Files also get 64 sectors in each cluster allocated to them.
  • RECOVER Fixed/Floppy Disk v3.0 Release 3 and RECOVER Fixed/Floppy Disk v2.2 - Technical Support Page 15 January 2010 7:15 UTC www.bestdiskrecovery.com [Source type: Reference]

^ The fact that they are marked as bad means that the system prevents the disk from using them, so previously identified bad sectors pose no danger to your data.
  • Troubleshooting Tools and Strategies 15 January 2010 7:15 UTC technet.microsoft.com [Source type: Reference]

^ Regular directories can have an arbitrary size; they use space on the disk much the way files do, and when more space is needed to hold more entries, the directory can be expanded the same way a file can.
  • http://euclid.nmu.edu/~randy/Classes/CS426/Notes/FileSystems/vfat-file-system.html 15 January 2010 7:15 UTC euclid.nmu.edu [Source type: Reference]

.FAT12 remains in use on all common floppy disks, including 1.44MB ones.^ All 5.25-inch floppy disks are formatted with FAT12, and 1.44-MB 3.5-inch floppy disks are generally formatted with FAT12.

^ Use a floppy disk, if you have one on your system, or use a spare disk.
  • Fragmentation: Chapter 2 15 January 2010 7:15 UTC www.diskeeper.com [Source type: FILTERED WITH BAYES]

^ FAT16 is not recommended for volumes larger than 511 MB because, when relatively small files are placed on a FAT16 volume, FAT uses disk space inefficiently.

Initial FAT16

.In 1984, IBM released the PC AT, which featured a 20 MB hard disk.^ In 1984 IBM released the PC AT, which featured a 20 MB hard disk.
  • - FAT12, FAT16 and FAT32 Windows File System 15 January 2010 7:15 UTC www.dataraid.com [Source type: Reference]

^ Hard disk data recovery and floppy disk data recovery cannot be cheaper than $20 USD which is the price of RECOVER Fixed/Floppy Disk v3.0 Release 3 and $15 USD which is the price of RECOVER Fixed/Floppy Disk v2.2.
  • RECOVER Fixed/Floppy Disk v3.0 Release 3 and RECOVER Fixed/Floppy Disk v2.2 - Technical Support Page 15 January 2010 7:15 UTC www.bestdiskrecovery.com [Source type: Reference]

^ RECOVER Fixed/Floppy Disk v3.0 Release 3 and RECOVER Fixed/Floppy Disk v2.2 are for recovering files from damaged floppy disks and hard disks.
  • RECOVER Fixed/Floppy Disk v3.0 Release 3 and RECOVER Fixed/Floppy Disk v2.2 - Technical Support Page 15 January 2010 7:15 UTC www.bestdiskrecovery.com [Source type: Reference]

.Microsoft introduced MS-DOS 3.0 in parallel.^ Microsoft introduced MS-DOS 3.0 in parallel.
  • - FAT12, FAT16 and FAT32 Windows File System 15 January 2010 7:15 UTC www.dataraid.com [Source type: Reference]

^ Microsoft has now made available MS-DOS version 2.0 to all OEM (original equipment manufacturer) customers of previous versions.

^ Since Microsoft has announced the discontinuation of its MS-DOS -based consumer operating systems with Windows Me, it remains unlikely that any new versions of FAT will appear.
  • - FAT12, FAT16 and FAT32 Windows File System 15 January 2010 7:15 UTC www.dataraid.com [Source type: Reference]

.(The earlier PC XT was the first PC with a hard drive from IBM, and MS-DOS 2.0 supported that hard drive with FAT12.) Cluster addresses were increased to 16-bit, allowing for up to 65,517 clusters per volume, and consequently much greater file system sizes, at least in theory.^ The minimum requirement to allow a file system to scale beyond 4GB in size is support for sizes beyond 32-bits.
  • Scalability and Performance in Modern Filesystems 15 January 2010 7:15 UTC oss.sgi.com [Source type: Reference]

^ Displays media file system volumes.
  • Cisco ACNS Software Deployment and Configuration Guide, Release 5.0 - Appendix A: Disk Space-Allocation Guidelines  [Cisco Application and Content Networking System (ACNS) Software] - Cisco Systems 15 January 2010 7:15 UTC www.cisco.com [Source type: Reference]
  • Cisco ACNS Software Maintenance and Troubleshooting Guide, Release 4.x - Chapter 2: Cisco ACNS Disk Space Allocation Guidelines  [Cisco Application and Content Networking System (ACNS) Software] - Cisco Systems 15 January 2010 7:15 UTC www.cisco.com [Source type: Reference]

^ XFS also allows the logical block size of the file system to be set on a per file system basis.
  • Scalability and Performance in Modern Filesystems 15 January 2010 7:15 UTC oss.sgi.com [Source type: Reference]

.However, the maximum possible number of sectors and the maximum (partition, rather than disk) size of 32 MB did not change.^ However, the maximum possible number of sectors and the maximum (partition, rather than disk) size of 32 MB did not change.
  • - FAT12, FAT16 and FAT32 Windows File System 15 January 2010 7:15 UTC www.dataraid.com [Source type: Reference]

^ The disk addresses are 32 bits in size.
  • General Programming Concepts: Writing and Debugging Programs - JFS File Space Allocation 15 January 2010 7:15 UTC www.ncsa.illinois.edu [Source type: Reference]

^ The partition size was now limited by the 8-bit signed count of sectors per cluster, which could reach a maximum power-of-two value of 64, giving 32 KB clusters with the usual 512 bytes per sector, hence fixing the "definitive" limit for FAT16 partition size at 2 gigabytes .
  • - FAT12, FAT16 and FAT32 Windows File System 15 January 2010 7:15 UTC www.dataraid.com [Source type: Reference]

.Therefore, although technically already "FAT16", this format was not what today is commonly understood as FAT16. With the initial implementation of FAT16 not actually providing for larger partition sizes than FAT12, the early benefit of FAT16 was to enable the use of smaller clusters, making disk usage more efficient, particularly for files several hundred bytes in size, which were far more common at the time.^ If a volume uses clusters that contain 8,192 bytes, an 8,000 byte file will use one cluster, or 8,192 bytes on the disk.
  • Hard Drive Clusters and File Allocation 15 January 2010 7:15 UTC www.dewassoc.com [Source type: Reference]

^ Average seek time should fall when using smaller partitions.
  • large allocation unit (FAT32/NTFS Clusters) 15 January 2010 7:15 UTC www.computing.net [Source type: FILTERED WITH BAYES]

^ Today, several journaling file systems are actively used.
  • Anatomy of Linux journaling file systems 15 January 2010 7:15 UTC www.ibm.com [Source type: Academic]

.Also, the introduction of FAT16 actually did bring an increase in the maximum partition size under MS-DOS, since the implementation of FAT12 for hard disks in MS-DOS 2.0 was limited to 15 MB. (That is, the initial FAT16 did not support larger drives than FAT12, but MS-DOS 3.0 using FAT16 did support larger drives than MS-DOS 2.0 using FAT12, by a factor of two.^ In heavy insert scenarios, this drives larger block sizes to the disk.
  • How many files should a database have? - Part 1: OLAP workloads - Technical Notes 15 January 2010 7:15 UTC sqlcat.com [Source type: FILTERED WITH BAYES]

^ Windows FAT partition hard disk drive ...
  • Search results for : free vista mbr files (page 1). - FreeVistaFiles.com 15 January 2010 7:15 UTC www.freevistafiles.com [Source type: General]

^ The JFS log is limited to a maximum size of 256 MB. .
  • System Management Concepts:Operating System and Devices - File System Types 15 January 2010 7:15 UTC moka.ccr.jussieu.fr [Source type: Reference]

)[11]
.A 20 MB hard disk formatted under MS-DOS 3.0 was not accessible by the older MS-DOS 2.0. (This was because MS-DOS 2.0 did not support version 3.0's FAT-16 and because it did not support hard disk partitions over 15 MB in size.^ Support major branded hard disk: .
  • Windows FAT data retrieval software restore retrieve deleted formatted file allocation table 15 January 2010 7:15 UTC www.f-find.com [Source type: Reference]

^ The format of the FAT itself did not change.
  • - FAT12, FAT16 and FAT32 Windows File System 15 January 2010 7:15 UTC www.dataraid.com [Source type: Reference]

^ The FAT file system is considered relatively uncomplicated, and because of that, it is a popular format for floppy disks ; moreover, it is supported by virtually all existing operating systems for personal computers , and because of that, it is often used to share data between several operating systems booting on the same computer (a multiboot environment).
  • - FAT12, FAT16 and FAT32 Windows File System 15 January 2010 7:15 UTC www.dataraid.com [Source type: Reference]

) .Of course, MS-DOS 3.0 could still access MS-DOS 2.0 style 8 KB-cluster partitions.^ The BAT works much like the MS-DOS File Allocation Table in that it is simply a linked list, where the link value at BAT(n) points to the next BAT entry used by the cluster.
  • Dr. Dobb's | A Random Access Compressed File Layer | July 1, 2001 15 January 2010 7:15 UTC www.ddj.com [Source type: FILTERED WITH BAYES]

^ It would keep doing this until it reached the cluster that had FFF stored, and it would know that this meant it had found the end of the file and could stop.
  • DOS Lesson 9: The File System : Ahuka Communications 15 January 2010 7:15 UTC www.ahuka.com [Source type: Reference]

^ Undelete utilities try to directly access the hardware, which cannot be done under Windows NT. However, if the file was located on a FAT partition, and the system is restarted under MS-DOS, the file can be undeleted.
  • Overview of FAT, HPFS, and NTFS File Systems 15 January 2010 7:15 UTC support.microsoft.com [Source type: Reference]

.MS-DOS 3.0 also introduced support for high-density 1.2 MB 5.25" diskettes, which notably had 15 sectors per track, hence more space for the FATs.^ Microsoft introduced MS-DOS 3.0 in parallel.
  • - FAT12, FAT16 and FAT32 Windows File System 15 January 2010 7:15 UTC www.dataraid.com [Source type: Reference]

^ MS-DOS 3.0 also introduced support for high-density 1.2 MB 5.25" diskettes, which notably had 15 sectors per track, hence more space for FAT. This probably prompted a dubious optimization of the cluster size, which went down from 2 sectors to just 1.
  • - FAT12, FAT16 and FAT32 Windows File System 15 January 2010 7:15 UTC www.dataraid.com [Source type: Reference]

^ The allocation unit is the smallest unit of space MS-DOS can keep track of.

.This probably prompted a dubious optimization of the cluster size, which went down from 2 sectors to just 1. The net effect was that high density diskettes were significantly slower than older double density ones.^ It deals with sector size, cluster and the power of 2.
  • max files directories of windows-family : max, directory, files 15 January 2010 7:15 UTC www.experts-exchange.com [Source type: FILTERED WITH BAYES]

^ MS-DOS 3.0 also introduced support for high-density 1.2 MB 5.25" diskettes, which notably had 15 sectors per track, hence more space for FAT. This probably prompted a dubious optimization of the cluster size, which went down from 2 sectors to just 1.
  • - FAT12, FAT16 and FAT32 Windows File System 15 January 2010 7:15 UTC www.dataraid.com [Source type: Reference]

^ The net effect was that high density diskettes were significantly slower than older double density ones.
  • - FAT12, FAT16 and FAT32 Windows File System 15 January 2010 7:15 UTC www.dataraid.com [Source type: Reference]

Extended partition and logical drives

.Apart from improving the structure of the FAT file system itself, a parallel development allowing an increase in the maximum possible FAT size was the introduction of multiple FAT partitions.^ The theoretical Maximum partition size for the FAT32 file system is 8 Terabytes.
  • Pandora Recovery features. Find and recover deleted files of any type - free. 15 January 2010 7:15 UTC www.pandorarecovery.com [Source type: Reference]

^ Increase the maximum size of a System V shared memory region ( Section 5.4.4 ) .
  • Tuning System Resource Allocation 15 January 2010 7:15 UTC h30097.www3.hp.com [Source type: Reference]

^ The maximum JFS size is defined when the file system is created.
  • System Management Concepts:Operating System and Devices - File System Types 15 January 2010 7:15 UTC moka.ccr.jussieu.fr [Source type: Reference]

.Originally DOS was only prepared to handle one FAT partition, although it came with documentation and programming tools for the creation of installable device drivers to handle multiple partitions, and third-party suppliers quickly provided the missing software.^ Third-party drivers?
  • Microsoft licenses another flash file format | Beyond Binary - CNET News 15 January 2010 7:15 UTC news.cnet.com [Source type: General]

^ For devices not directly supported under the Solaris OS, such as certain automated library and optical disk devices, Sun Microsystems provides special device drivers in the Sun StorageTek SAM software package.
  • C H A P T E R 1 - File System Overview 15 January 2010 7:15 UTC docs.sun.com [Source type: Reference]

^ In one embodiment of a TFAT volume, when a first cluster is allocated for a new directory or subdirectory, only two DIRENTRYs (‘.’ and ‘..’ entries) are written when the new directory or subdirectory is created (block 310 ).
  • Transaction-safe FAT file system - Patent 7174420 15 January 2010 7:15 UTC www.freepatentsonline.com [Source type: Reference]

.Aside from that, partitions were used for sharing the disk between operating systems, typically DOS and Xenix at the time.^ In what operating systems NTFS is used?
  • Pandora File Recovery support page. Recover deleted files of any type - free. 15 January 2010 7:15 UTC www.pandorarecovery.com [Source type: Reference]

^ The fact that they are marked as bad means that the system prevents the disk from using them, so previously identified bad sectors pose no danger to your data.
  • Troubleshooting Tools and Strategies 15 January 2010 7:15 UTC technet.microsoft.com [Source type: Reference]

^ The FAT file system is considered relatively uncomplicated, and because of that, it is a popular format for floppy disks ; moreover, it is supported by virtually all existing operating systems for personal computers , and because of that, it is often used to share data between several operating systems booting on the same computer (a multiboot environment).
  • - FAT12, FAT16 and FAT32 Windows File System 15 January 2010 7:15 UTC www.dataraid.com [Source type: Reference]

.Extra DOS partitions could not be used as boot partitions, because the installable device drivers were loaded (in config.sys) only after the first part of the DOS boot process.^ Only the primary DOS partitions are recorded in the first block of a disk.

^ Because conventional file systems assume that the storage device has the multiple-write capability, these file systems are not appropriate for the FEProm, which effectively has only a single-write capability.
  • Method and system for file system management using a flash-erasable, programmable, read-only memory - Patent 6256642 15 January 2010 7:15 UTC www.freepatentsonline.com [Source type: Reference]

^ Tells the FAT driver to read the Master Boot Recotd (MBR), partition table and boot record, in that order.
  • An #127 - FAT16 File System Driver for CompactFlash - MCS Electronics 15 January 2010 7:15 UTC www.mcselec.com [Source type: Reference]

.Later, third party tools became available that replaced the DOS master boot record (MBR) and directly loaded non-DOS drivers before DOS: such systems generally came with careful warnings that without the 3rd party software, the disk would not be compatible with DOS. Simply allowing several identical-looking DOS partitions could lead to naming problems: behaviour if more than one partition was marked active was undocumented (although well defined), as was the behaviour if there was more than one hard disk in the computer (which was machine dependent), or if the system was booted from a diskette.^ Tells the FAT driver to read the Master Boot Recotd (MBR), partition table and boot record, in that order.
  • An #127 - FAT16 File System Driver for CompactFlash - MCS Electronics 15 January 2010 7:15 UTC www.mcselec.com [Source type: Reference]

^ Only the primary DOS partitions are recorded in the first block of a disk.

^ This "Boot" record will be described in more detail later.

.To allow the use of more FAT partitions in a compatible way, a new partition type was introduced (in MS-DOS 3.2, January 1986), the extended partition, which is a container for additional partitions called logical drives.^ MS/DOS and OS/2 use this scheme.
  • Operating Systems Lecture Notes Lecture 13 File System Implementation 15 January 2010 7:15 UTC people.csail.mit.edu [Source type: Reference]

^ Microsoft introduced MS-DOS 3.0 in parallel.
  • - FAT12, FAT16 and FAT32 Windows File System 15 January 2010 7:15 UTC www.dataraid.com [Source type: Reference]

^ MS-DOS 3.0 also introduced support for high-density 1.2 MB 5.25" diskettes, which notably had 15 sectors per track, hence more space for FAT. This probably prompted a dubious optimization of the cluster size, which went down from 2 sectors to just 1.
  • - FAT12, FAT16 and FAT32 Windows File System 15 January 2010 7:15 UTC www.dataraid.com [Source type: Reference]

.Originally only one logical drive was possible, permitting hard disks up to 64 MB. In MS-DOS 3.3 (August 1987) this limit was increased to 24 drives, equal to the maximum number of available letters for drive names (A and B being reserved for the first two floppy drives, at least one of which many, if not most, systems of the era were equipped with; where only one was installed, B always simulated a second drive using A).^ MS/DOS and OS/2 use this scheme.
  • Operating Systems Lecture Notes Lecture 13 File System Implementation 15 January 2010 7:15 UTC people.csail.mit.edu [Source type: Reference]

^ The file system on the floppy disk need not be one that was defragmented recently.
  • Systech Software - Floppy disk recovery, Hard disk recovery - Editor's Choice utilities 15 January 2010 7:15 UTC www.bestdiskrecovery.com [Source type: Reference]

^ Format the hard drive from the boot disk using the format command.
  • ActiveWindows -- Frequently Asked Questions - FAT32 ( File AllocationTable 32 ) 15 January 2010 7:15 UTC www.activewin.com [Source type: General]

.Logical drives are described by on-disk structures which closely resemble the Master Boot Record (MBR) of the disk (which describes the primary partitions), likely to simplify the implementation.^ Only the primary DOS partitions are recorded in the first block of a disk.

^ The master boot record contains the following structures: .
  • http://euclid.nmu.edu/~randy/Classes/CS426/Notes/FileSystems/vfat-file-system.html 15 January 2010 7:15 UTC euclid.nmu.edu [Source type: Reference]

^ The place where this information is stored is called the master boot record (MBR).
  • http://euclid.nmu.edu/~randy/Classes/CS426/Notes/FileSystems/vfat-file-system.html 15 January 2010 7:15 UTC euclid.nmu.edu [Source type: Reference]

.Though some believe these partitions were nested in a way analogous to Russian matryoshka dolls, that isn't the case.^ These two opposite types of variables require a sampling strategy that in some way balances the sample between numbers of establishments and numbers of employees.
  • Methodology Report #18: Updates to the Medical Expenditure Panel Survey Insurance Component List Sample Design, 2004 15 January 2010 7:15 UTC www.meps.ahrq.gov [Source type: Academic]

^ (Note: these numbers are approximate, since hard drive sizes are stated differently in some cases.
  • DOS Lesson 9: The File System : Ahuka Communications 15 January 2010 7:15 UTC www.ahuka.com [Source type: Reference]

^ So there is some incentive to minimize this wastage, and the best way is reduce the size of the partition.
  • DOS Lesson 9: The File System : Ahuka Communications 15 January 2010 7:15 UTC www.ahuka.com [Source type: Reference]

.They are stored as a row of separate blocks within a single box; these blocks are often referred to as being chained together, by the links in their extended boot record (EBR) sectors.^ Since clusters are linked one to another in this manner, they are referred to as being chained.
  • Hard Drive Clusters and File Allocation 15 January 2010 7:15 UTC www.dewassoc.com [Source type: Reference]

^ These clusters are linked together in a cluster chain.
  • An #127 - FAT16 File System Driver for CompactFlash - MCS Electronics 15 January 2010 7:15 UTC www.mcselec.com [Source type: Reference]

^ The elements in these chains refer to blocks in the files.
  • POIFS File System Internals 15 January 2010 7:15 UTC poi.apache.org [Source type: Reference]

.Only one extended partition is allowed.^ Aggregates may contain one or more filesets , but currently only one is allowed.
  • Notes about Linux file systems 15 January 2010 7:15 UTC www.sabi.co.uk [Source type: Reference]
  • JFS Filesystem 15 January 2010 7:15 UTC www.softpanorama.org [Source type: Reference]

^ The program's partition file system previewers not only allow identification and assessment of candidate partitions but can recover or undelete files from damaged...
  • Master File Table Download - Free Download Master File Table 15 January 2010 7:15 UTC www.softlist.net [Source type: General]

^ If you noted above that only 8 bytes are reserved for the file name in each entry, and if you realized that each character requires one byte to describe it, you quickly see why DOS only allows 8 character file names.
  • DOS Lesson 9: The File System : Ahuka Communications 15 January 2010 7:15 UTC www.ahuka.com [Source type: Reference]

.Under MS-DOS, logical drives are not bootable, and the extended partition can only be created after the primary FAT partition, which removes all ambiguity but also eliminates the possibility of booting several DOS versions from the same hard disk.^ The extended DOS partition table is placed elsewhere on a disk.

^ Only the primary DOS partitions are recorded in the first block of a disk.

^ Removable hard drive partition repair tool performs complete...
  • file allocation table Resources | ZDNet 15 January 2010 7:15 UTC updates.zdnet.com [Source type: General]

.(A few systems other than MS-DOS can boot logical drives, and partitions can be created in any order using third party formatting tools.^ Drives formatted by DOS or Windows have at least one partition, labeled "C:".
  • Untitled Document 15 January 2010 7:15 UTC www.lc-tech.com [Source type: Reference]

^ MS/DOS and OS/2 use this scheme.
  • Operating Systems Lecture Notes Lecture 13 File System Implementation 15 January 2010 7:15 UTC people.csail.mit.edu [Source type: Reference]

^ Format the hard drive from the boot disk using the format command.
  • ActiveWindows -- Frequently Asked Questions - FAT32 ( File AllocationTable 32 ) 15 January 2010 7:15 UTC www.activewin.com [Source type: General]

)
.A useful side-effect of the extended partition scheme was to significantly increase the maximum number of partitions possible on a PC hard disk beyond the four which could be described by the MBR alone.^ Blocks are numbered such that a small number are used from each disk or partition in succession.
  • Scalability and Performance in Modern Filesystems 15 January 2010 7:15 UTC oss.sgi.com [Source type: Reference]

^ If you dont have a spare hard disk letter, but you have unpartitioned space on your hard disk, create a new partition, set it up as an extended partition and format it as a logical drive with the FAT file system (FAT16 or FAT32).
  • InformIT: Data Protection and Recovery Techniques Part 6: Recovering Data Without Help from the FATLearn how to identify and restore files on a disk with a missing or damaged file allocation table (FAT) > Data Protection and Recovery Techniques Part 6: Recovering Data Without Help from the FAT Learn how to identify and restore files on a disk with a missing or damaged file allocation table (FAT) 15 January 2010 7:15 UTC www.informit.com [Source type: Reference]

^ For example, the standard format for 8-inch single-density disks uses four 128-byte sectors per allocation unit.

.Prior to the introduction of extended partitions, some hard disk controllers (which at that time were usually separate option boards) could make large hard disks appear at the hardware interface level as two separate disks.^ On any large hard disk, there are apt to be some bad spots.
  • A Description of the DOS File System 15 January 2010 7:15 UTC alumni.caltech.edu [Source type: Reference]

^ However, floppy disk controllers and some hard disk controllers cannot do this.
  • A Description of the DOS File System 15 January 2010 7:15 UTC alumni.caltech.edu [Source type: Reference]

^ Small to large hard disk volumes .
  • An #127 - FAT16 File System Driver for CompactFlash - MCS Electronics 15 January 2010 7:15 UTC www.mcselec.com [Source type: Reference]

.Otherwise, DOS "Block Device Drivers" were used to access the other 3 possible partitions on a disk.^ Blocks are numbered such that a small number are used from each disk or partition in succession.
  • Scalability and Performance in Modern Filesystems 15 January 2010 7:15 UTC oss.sgi.com [Source type: Reference]

^ Only the primary DOS partitions are recorded in the first block of a disk.

^ Any other method may be used, and MS-DOS wouldn't know the difference.

Final FAT16

.Finally in November 1987, Compaq DOS 3.31 (an OEM version of MS-DOS 3.3 released by Compaq with their machines) introduced what is today called the FAT16 format, with the expansion of the 16-bit disk sector count to 32 bits.^ Microsoft introduced MS-DOS 3.0 in parallel.
  • - FAT12, FAT16 and FAT32 Windows File System 15 January 2010 7:15 UTC www.dataraid.com [Source type: Reference]

^ In 1987 finally came what today is called the FAT16 format, with the removal of the 16-bit counter of disk sectors, in Compaq DOS 3.31.
  • - FAT12, FAT16 and FAT32 Windows File System 15 January 2010 7:15 UTC www.dataraid.com [Source type: Reference]

^ The disk addresses are 32 bits in size.
  • General Programming Concepts: Writing and Debugging Programs - JFS File Space Allocation 15 January 2010 7:15 UTC www.ncsa.illinois.edu [Source type: Reference]

.The result was initially called the DOS 3.31 Large File System.^ A DOS file system resides on what is generally called a block device.
  • A Description of the DOS File System 15 January 2010 7:15 UTC alumni.caltech.edu [Source type: Reference]

^ This feature minimizes the system overhead caused by read-modify-write operations and is therefore particularly useful for applications that manipulate very large files.
  • C H A P T E R 1 - File System Overview 15 January 2010 7:15 UTC docs.sun.com [Source type: Reference]
  • C H A P T E R 1 - File System Overview 15 January 2010 7:15 UTC docs.sun.com [Source type: Reference]
  • File System Design Basics - SAM-QFS Documentation - wikis.sun.com 15 January 2010 7:15 UTC wikis.sun.com [Source type: Reference]

^ This cannot happen in the MS-DOS file system because MS-DOS does not require files to be allocated contiguously.

.Although the on-disk changes were minor, the entire DOS disk driver had to be converted to use 32-bit sector numbers, a task complicated by the fact that it was written in 16-bit assembly language.^ The last design requirement was that MS-DOS be written in assembly language.

^ Otherwise, 16-bit entries are used.
  • A Description of the DOS File System 15 January 2010 7:15 UTC alumni.caltech.edu [Source type: Reference]

^ The disk addresses are 32 bits in size.
  • General Programming Concepts: Writing and Debugging Programs - JFS File Space Allocation 15 January 2010 7:15 UTC www.ncsa.illinois.edu [Source type: Reference]

.In 1988 this improvement became more generally available through MS-DOS 4.0 and OS/2 1.1. The limit on partition size was dictated by the 8-bit signed count of sectors per cluster, which had a maximum power-of-two value of 64. With the standard hard disk sector size of 512 bytes, this gives a maximum of 32 KB clusters, thereby fixing the "definitive" limit for the FAT16 partition size at 2 gigabytes.^ Sectors per cluster (Must be a power of 2 and cluster size must be <=32 KB) .
  • The FAT File System 15 January 2010 7:15 UTC www.c-jump.com [Source type: Reference]

^ Physical disk blocks typically 512 bytes in size.
  • Scalability and Performance in Modern Filesystems 15 January 2010 7:15 UTC oss.sgi.com [Source type: Reference]

^ It deals with sector size, cluster and the power of 2.
  • max files directories of windows-family : max, directory, files 15 January 2010 7:15 UTC www.experts-exchange.com [Source type: FILTERED WITH BAYES]

.On magneto-optical media, which can have 1 or 2 KB sectors instead of 1/2 KB, this size limit is proportionally larger.^ Disk Parameter Block : Also sometimes called the media parameter block, this is a data table that contains specific information about the volume, such as its specifications (size, number of sectors it contains, etc.
  • http://euclid.nmu.edu/~randy/Classes/CS426/Notes/FileSystems/vfat-file-system.html 15 January 2010 7:15 UTC euclid.nmu.edu [Source type: Reference]

^ Sectors per cluster (Must be a power of 2 and cluster size must be <=32 KB) .
  • The FAT File System 15 January 2010 7:15 UTC www.c-jump.com [Source type: Reference]

^ The size of a FAT32 cluster can range in size from 1 sector (512 bytes) to 64 sectors (32 KB), incremented in powers of 2.

.Much later, Windows NT increased the maximum cluster size to 64 KB by considering the sectors-per-cluster count as unsigned.^ Sectors per cluster (Must be a power of 2 and cluster size must be <=32 KB) .
  • The FAT File System 15 January 2010 7:15 UTC www.c-jump.com [Source type: Reference]

^ That is, 64 sectors * 16 entries per sector.
  • RECOVER Fixed/Floppy Disk v3.0 Release 3 and RECOVER Fixed/Floppy Disk v2.2 - Technical Support Page 15 January 2010 7:15 UTC www.bestdiskrecovery.com [Source type: Reference]

^ Files also get 64 sectors in each cluster allocated to them.
  • RECOVER Fixed/Floppy Disk v3.0 Release 3 and RECOVER Fixed/Floppy Disk v2.2 - Technical Support Page 15 January 2010 7:15 UTC www.bestdiskrecovery.com [Source type: Reference]

.However, the resulting format was not compatible with any other FAT implementation of the time, and it generated greater internal fragmentation.^ However the resulting format was not compatible with any other FAT implementation of the time and generated really huge internal fragmentation anyway.
  • - FAT12, FAT16 and FAT32 Windows File System 15 January 2010 7:15 UTC www.dataraid.com [Source type: Reference]

^ To provide maximum usable data space on the disk, both internal fragmentation and FAT size must be considered because both consume data area.

^ But what about the 100 times greater overhead required to access fragmented files?
  • Fragmentation: Chapter 2 15 January 2010 7:15 UTC www.diskeeper.com [Source type: FILTERED WITH BAYES]

.Windows 98 also supported reading and writing this variant, but its disk utilities did not work with it.^ Windows 98 also supported reading and writing this variant but its disk utilities didn't work with it.
  • - FAT12, FAT16 and FAT32 Windows File System 15 January 2010 7:15 UTC www.dataraid.com [Source type: Reference]

^ But I'd like to minimize these issues by using a filesystem that has the best multi-OS support for both reading and writing, while at the same time supporting large files."
  • Slashdot Ask Slashdot Story | Best Filesystem For External Back-Up Drives? 15 January 2010 7:15 UTC ask.slashdot.org [Source type: General]

^ Windows 98 introduced a utility to convert existing hard disks from FAT16 to FAT32 without loss of data.
  • - FAT12, FAT16 and FAT32 Windows File System 15 January 2010 7:15 UTC www.dataraid.com [Source type: Reference]

.The number of root directory entries available is determined when the volume is formatted, and is stored in a 16-bit signed field, defining an absolute limit of 32767 entries (32736, a multiple of 32, in practice).^ Root directory is set at 32 sectors .
  • The FAT File System 15 January 2010 7:15 UTC www.c-jump.com [Source type: Reference]

^ The type is 1 for directory, 2 for file or 5 for the Root Entry.
  • POIFS File System Internals 15 January 2010 7:15 UTC poi.apache.org [Source type: Reference]

^ This number, together with the sector size, determines the number of sectors allocated to the root directory.
  • A Description of the DOS File System 15 January 2010 7:15 UTC alumni.caltech.edu [Source type: Reference]

.For historical reasons, FAT12 and FAT16 media generally use 512 root directory entries on non-floppy media.^ The type is 1 for directory, 2 for file or 5 for the Root Entry.
  • POIFS File System Internals 15 January 2010 7:15 UTC poi.apache.org [Source type: Reference]

^ This is used by files and the root entry.
  • POIFS File System Internals 15 January 2010 7:15 UTC poi.apache.org [Source type: Reference]

^ FAT12 = 512 files in root?
  • max files directories of windows-family : max, directory, files 15 January 2010 7:15 UTC www.experts-exchange.com [Source type: FILTERED WITH BAYES]

.Other sizes may be incompatible with some software or devices (entries being file and/or folder names in the original 8.3 format).^ A file will have an entry for each name change.
  • Method and system for file system management using a flash-erasable, programmable, read-only memory - Patent 6256642 15 January 2010 7:15 UTC www.freepatentsonline.com [Source type: Reference]

^ The size of the file being written determines the I/O size.
  • C H A P T E R 1 - File System Overview 15 January 2010 7:15 UTC docs.sun.com [Source type: Reference]
  • C H A P T E R 1 - File System Overview 15 January 2010 7:15 UTC docs.sun.com [Source type: Reference]

^ Recovered files and folders are saved in their original Long File Name (LFN) format names.
  • Systech Software - Floppy disk recovery, Hard disk recovery - Editor's Choice utilities 15 January 2010 7:15 UTC www.bestdiskrecovery.com [Source type: Reference]

[12] .Some third party tools like mkdosfs allow the user to set this parameter.^ In some embodiments the flash memory will allow successive write operations to a single location if the write operation turns off bits that are currently set (i.e., changes the bit from a binary "1" value to a binary "0" value).
  • FILE ALLOCATION TABLE MANAGEMENT - Patent application - In one embodiment a storage controller comprises a first port that provides an interface to a host computer 15 January 2010 7:15 UTC www.faqs.org [Source type: Reference]

^ If the files are kept together in adjacent clusters, the chances of recovering them, even with third-party recovery tools, increases measurably.
  • Hard Drive Clusters and File Allocation 15 January 2010 7:15 UTC www.dewassoc.com [Source type: Reference]

^ What third party tools can be used with Oracle EBU/ RMAN? (for DBA Why and when should one tune?
  • How does Space allocation table place within a b 15 January 2010 7:15 UTC dev.fyicenter.com [Source type: Reference]

[13]

Long file names

.One of the user experience goals for the designers of Windows 95 was the ability to use long filenames (LFNs—up to 255 UTF-16 code points long), in addition to classic 8.3 filenames.^ One of the user experience goals for the designers of Windows 95 was the use of long file names in the new operating system.
  • - FAT12, FAT16 and FAT32 Windows File System 15 January 2010 7:15 UTC www.dataraid.com [Source type: Reference]

^ Additional 32B entries contain the file's long filename (LFN) .
  • The FAT File System 15 January 2010 7:15 UTC www.c-jump.com [Source type: Reference]

^ It is commonly confused with LFN support, as almost nobody configured Windows 3.11 to use VFAT and it was automatically enabled (and was also enhanced to support LFNs) in Windows 95.
  • - FAT12, FAT16 and FAT32 Windows File System 15 January 2010 7:15 UTC www.dataraid.com [Source type: Reference]

.LFNs were implemented using a workaround in the way directory entries are laid out (see below).^ These were implemented using a work-around in the way directory entries are laid out (see below).
  • - FAT12, FAT16 and FAT32 Windows File System 15 January 2010 7:15 UTC www.dataraid.com [Source type: Reference]

^ For instructions on use, see below .

^ LFN entries use the following format: .
  • - FAT12, FAT16 and FAT32 Windows File System 15 January 2010 7:15 UTC www.dataraid.com [Source type: Reference]

.The version of the file system with this extension is usually known as VFAT after the Windows 95 virtual device driver, also known as "Virtual FAT" in Microsoft's documentation.^ Here's an example: Windows 95 users rely on the FAT 16 file system.
  • Clusters, Sectors & Tables - Review Tom's Hardware : The WinFS File System For Windows Longhorn: Faster & Smarter 15 January 2010 7:15 UTC www.tomshardware.com [Source type: General]

^ The File System Configuration window appears.
  • Cisco ACNS Software Deployment and Configuration Guide, Release 5.0 - Appendix A: Disk Space-Allocation Guidelines  [Cisco Application and Content Networking System (ACNS) Software] - Cisco Systems 15 January 2010 7:15 UTC www.cisco.com [Source type: Reference]

^ NTFS : The file system designed by Microsoft for Windows NT. .
  • Scalability and Performance in Modern Filesystems 15 January 2010 7:15 UTC oss.sgi.com [Source type: Reference]

.Interestingly, the VFAT driver actually appeared before Windows 95, in Windows for Workgroups 3.11, but was only used for implementing 32-bit file access and did not support long file names.^ GB 32-bit Windows XP .
  • Mark's Blog 15 January 2010 7:15 UTC blogs.technet.com [Source type: FILTERED WITH BAYES]

^ If Long File Name support is available, Long File Name format is used when recovering and saving files with long filenames.
  • Systech Software - Floppy disk recovery, Hard disk recovery - Editor's Choice utilities 15 January 2010 7:15 UTC www.bestdiskrecovery.com [Source type: Reference]

^ File size (32 bits).

.In Windows NT, support for long filenames on FAT started from version 3.5.^ Long file names are also supported Windows NT 3.5 ( FASTFAT 1.1) and above.
  • - FAT12, FAT16 and FAT32 Windows File System 15 January 2010 7:15 UTC www.dataraid.com [Source type: Reference]

^ For all versions, Windows supports up to 16 paging files, where each must be on a separate volume.
  • Mark's Blog : Pushing the Limits of Windows: Virtual Memory 15 January 2010 7:15 UTC blogs.technet.com [Source type: FILTERED WITH BAYES]
  • Mark's Blog 15 January 2010 7:15 UTC blogs.technet.com [Source type: FILTERED WITH BAYES]

^ For more information about the supported file systems for Windows NT, please see the Windows NT Resource Kit.
  • Overview of FAT, HPFS, and NTFS File Systems 15 January 2010 7:15 UTC support.microsoft.com [Source type: Reference]

.OS/2 added long filename support to FAT using extended attributes (EA) before the introduction of VFAT; thus, VFAT long filenames are invisible to OS/2, and EA long filenames are invisible to Windows.^ Using FAT with Windows 2000 .

^ It is commonly confused with LFN support, as almost nobody configured Windows 3.11 to use VFAT and it was automatically enabled (and was also enhanced to support LFNs) in Windows 95.
  • - FAT12, FAT16 and FAT32 Windows File System 15 January 2010 7:15 UTC www.dataraid.com [Source type: Reference]

^ But I'd like to minimize these issues by using a filesystem that has the best multi-OS support for both reading and writing, while at the same time supporting large files."
  • Slashdot Ask Slashdot Story | Best Filesystem For External Back-Up Drives? 15 January 2010 7:15 UTC ask.slashdot.org [Source type: General]

FAT32

.In order to overcome size limit of FAT16, while at the same time allowing DOS real mode code to handle the format, and without reducing available conventional memory unnecessarily, Microsoft implemented a next generation, known as FAT32.^ This time I’m going to go inside the implementation of handles to find and explain their limits.
  • Mark's Blog 15 January 2010 7:15 UTC blogs.technet.com [Source type: FILTERED WITH BAYES]

^ In order to overcome the volume size limit of FAT16 while still allowing DOS real-mode code to handle the format without unnessacerally reducing the availible conventional memory , Microsoft decided to implement a newer generation of FAT, known as FAT32 , with 32-bit cluster numbers, of which 28 bits are currently used.
  • - FAT12, FAT16 and FAT32 Windows File System 15 January 2010 7:15 UTC www.dataraid.com [Source type: Reference]

^ (This mode on the 20D is a little different from the implementation used by other camera makers, in that it makes use of a previously-shot image of a white card, allowing you to store several white-point references on the camera's memory card and switch between them.
  • Canon EOS 20D Digital Camera Review: Camera Modes & Menus 15 January 2010 7:15 UTC www.imaging-resource.com [Source type: General]

.Cluster values are represented by 32-bit numbers, of which 28 bits are used to hold the cluster number, for a maximum of approximately 268 million (228) clusters.^ Each entry contains a value that represents how the cluster is being used.
  • http://euclid.nmu.edu/~randy/Classes/CS426/Notes/FileSystems/vfat-file-system.html 15 January 2010 7:15 UTC euclid.nmu.edu [Source type: Reference]

^ Note that FAT32 uses only 28 bits of the 32 possible bits.
  • - FAT12, FAT16 and FAT32 Windows File System 15 January 2010 7:15 UTC www.dataraid.com [Source type: Reference]

^ The partition size was now limited by the 8-bit signed count of sectors per cluster, which could reach a maximum power-of-two value of 64, giving 32 KB clusters with the usual 512 bytes per sector, hence fixing the "definitive" limit for FAT16 partition size at 2 gigabytes .
  • - FAT12, FAT16 and FAT32 Windows File System 15 January 2010 7:15 UTC www.dataraid.com [Source type: Reference]

.This allows for drive sizes of up to 8 terabytes with 32KB clusters, but the boot sector uses a 32-bit field for the sector count, limiting volume size to 2 TB on a hard disk with 512 byte sectors.^ Boot Sector is 1 sector (0x200 bytes) .
  • The FAT File System 15 January 2010 7:15 UTC www.c-jump.com [Source type: Reference]

^ Sectors per cluster (Must be a power of 2 and cluster size must be <=32 KB) .
  • The FAT File System 15 January 2010 7:15 UTC www.c-jump.com [Source type: Reference]

^ Physical disk blocks typically 512 bytes in size.
  • Scalability and Performance in Modern Filesystems 15 January 2010 7:15 UTC oss.sgi.com [Source type: Reference]

.On Windows 95/98, due to the version of Microsoft's SCANDISK utility included with these operating systems being a 16-bit application, the FAT structure is not allowed to grow beyond around 4.2 million (< 222) clusters, placing the volume limit at 127.53 GiB.^ Finally, here’s the limit on an 8GB 64-bit Windows 7 system: .
  • Mark's Blog 15 January 2010 7:15 UTC blogs.technet.com [Source type: FILTERED WITH BAYES]

^ (Operating system kernels are the usual application for these switches.
  • Storage allocation 15 January 2010 7:15 UTC www.iecc.com [Source type: FILTERED WITH BAYES]

^ However, due to limitations in Microsoft's scandisk utility, the FAT is not allowed to grow beyond 4,177,920 ( < 2 24 ) clusters, placing the volume limit at 124.55 gigabytes, unless "scandisk" is not needed.
  • - FAT12, FAT16 and FAT32 Windows File System 15 January 2010 7:15 UTC www.dataraid.com [Source type: Reference]

[14] .A limitation in original versions of Windows 98/98SE's Fdisk utility causes it to incorrectly report disk sizes over 64 GB.[15] A corrected version is available from Microsoft, but it cannot partition drives larger than 512GB [16].^ GB 64-bit Windows 7 .
  • Mark's Blog 15 January 2010 7:15 UTC blogs.technet.com [Source type: FILTERED WITH BAYES]

^ Size of your disk drive; 3.
  • Pandora File Recovery support page. Recover deleted files of any type - free. 15 January 2010 7:15 UTC www.pandorarecovery.com [Source type: Reference]

^ GB 64-bit Windows XP .
  • Mark's Blog 15 January 2010 7:15 UTC blogs.technet.com [Source type: FILTERED WITH BAYES]

.The Windows 2000/XP installation program and filesystem creation tool imposes a limitation of 32 GB [17].^ GB 32-bit Windows XP .
  • Mark's Blog 15 January 2010 7:15 UTC blogs.technet.com [Source type: FILTERED WITH BAYES]

^ GB 64-bit Windows XP .
  • Mark's Blog 15 January 2010 7:15 UTC blogs.technet.com [Source type: FILTERED WITH BAYES]

^ Available for all modern platforms, including Windows 95/98/ME/NT/2000/XP/2003 Server.
  • Damaged File Allocation Table downloads at VicMan 15 January 2010 7:15 UTC www.vicman.net [Source type: Reference]

.However, both systems can read and write to FAT32 file systems of any size.^ RT030 File system is read only.

^ The total size of the File System in bytes.
  • Using Default Tools - Database Tables 15 January 2010 7:15 UTC www.hp.com [Source type: Reference]

^ This feature minimizes the system overhead caused by read-modify-write operations and is therefore particularly useful for applications that manipulate very large files.
  • C H A P T E R 1 - File System Overview 15 January 2010 7:15 UTC docs.sun.com [Source type: Reference]
  • C H A P T E R 1 - File System Overview 15 January 2010 7:15 UTC docs.sun.com [Source type: Reference]
  • File System Design Basics - SAM-QFS Documentation - wikis.sun.com 15 January 2010 7:15 UTC wikis.sun.com [Source type: Reference]

.This limitation is by design and according to Microsoft was imposed because many tasks on a very large FAT32 file system become slow and inefficient.^ NTFS : The file system designed by Microsoft for Windows NT. .
  • Scalability and Performance in Modern Filesystems 15 January 2010 7:15 UTC oss.sgi.com [Source type: Reference]

^ This is why file system become fragmented.
  • large allocation unit (FAT32/NTFS Clusters) 15 January 2010 7:15 UTC www.computing.net [Source type: FILTERED WITH BAYES]

^ What are sources of inefficiency in this file system?
  • Operating Systems Lecture Notes Lecture 13 File System Implementation 15 January 2010 7:15 UTC people.csail.mit.edu [Source type: Reference]

[14][18] .This limitation can be bypassed by using third-party formatting utilities.^ A: Yes, by using some third party software or utilities.
  • ActiveWindows -- Frequently Asked Questions - FAT32 ( File AllocationTable 32 ) 15 January 2010 7:15 UTC www.activewin.com [Source type: General]

^ For this reason, you may not create a FAT32 volume larger than 32 GB using the Format utility.

^ What third party tools can be used with Oracle EBU/ RMAN? (for DBA Why and when should one tune?
  • How does Space allocation table place within a b 15 January 2010 7:15 UTC dev.fyicenter.com [Source type: Reference]

[19] .Windows Me supports the FAT32 file system without any limits.^ What file systems are supported by Pandora Recovery?
  • Pandora File Recovery support page. Recover deleted files of any type - free. 15 January 2010 7:15 UTC www.pandorarecovery.com [Source type: Reference]

^ Also, the FAT32 file system is only supported in the Windows 98/95 and Windows 2000.
  • Overview of FAT, HPFS, and NTFS File Systems 15 January 2010 7:15 UTC support.microsoft.com [Source type: Reference]

^ Support for FAT32 is new in Windows 2000.

[20] However, similarly to Windows 95/98/98SE there is no native support for 48-bit LBA in Windows ME, meaning that the maximum disk size for ATA disks is 127.6 GiB, the maximum size of an ATA disk using the previous long-standard 28-bit LBA.
.FAT32 was introduced with Windows 95 OSR2, although reformatting was needed to use it, and DriveSpace 3 (the version that came with Windows 95 OSR2 and Windows 98) never supported it.^ FAT32 works the same way in Windows 2000 as it does in Windows 95 OSR2 and Windows 98.

^ You can find FAT 32 in the OSR2 version of Windows 95.
  • ActiveWindows -- Frequently Asked Questions - FAT32 ( File AllocationTable 32 ) 15 January 2010 7:15 UTC www.activewin.com [Source type: General]

^ Also, Windows 98 ships with a FAT32 converter.
  • ActiveWindows -- Frequently Asked Questions - FAT32 ( File AllocationTable 32 ) 15 January 2010 7:15 UTC www.activewin.com [Source type: General]

.Windows 98 introduced a utility to convert existing hard disks from FAT16 to FAT32 without loss of data.^ Windows 98 introduced a utility to convert existing hard disks from FAT16 to FAT32 without loss of data.
  • - FAT12, FAT16 and FAT32 Windows File System 15 January 2010 7:15 UTC www.dataraid.com [Source type: Reference]

^ Also, Windows 98 ships with a FAT32 converter.
  • ActiveWindows -- Frequently Asked Questions - FAT32 ( File AllocationTable 32 ) 15 January 2010 7:15 UTC www.activewin.com [Source type: General]

^ While data is stored in 512-byte sectors on the hard disk, for performance reasons individual sectors are not normally allocated to files.
  • http://euclid.nmu.edu/~randy/Classes/CS426/Notes/FileSystems/vfat-file-system.html 15 January 2010 7:15 UTC euclid.nmu.edu [Source type: Reference]

.In the NT line, native support for FAT32 arrived in Windows 2000.^ Windows NT/2000/2003/2008 .

^ Support in the NT line came with Windows 2000.
  • - FAT12, FAT16 and FAT32 Windows File System 15 January 2010 7:15 UTC www.dataraid.com [Source type: Reference]

^ The FAT32 formatting support in Windows 2000 and XP is limited to drives of about 30 gigabytes, which effectively forces users of modern hard drives either to use NTFS or to format the drive using other tools outside Windows.
  • - FAT12, FAT16 and FAT32 Windows File System 15 January 2010 7:15 UTC www.dataraid.com [Source type: Reference]

.A free FAT32 driver for Windows NT 4.0 was available from Winternals, a company later acquired by Microsoft.^ You can enable it either by using the Application Verifier , a free download from Microsoft, or by using the Windows D ebugger (Windbg).
  • Mark's Blog 15 January 2010 7:15 UTC blogs.technet.com [Source type: FILTERED WITH BAYES]

^ However, the Windows 2000 Fastfat driver enables you to mount and fully support a FAT32 volume larger than 32 GB. .

^ Windows NT 3.1 provided the same approach, calling it FASTFAT , however in a different fashion as it is natural for a filesystem driver in NT to use 32-bit protected mode.
  • - FAT12, FAT16 and FAT32 Windows File System 15 January 2010 7:15 UTC www.dataraid.com [Source type: Reference]

Since the acquisition the driver is no longer officially available.
.The maximum possible size for a file on a FAT32 volume is 4 GB minus 1 byte (232−1 bytes).^ The maximum possible file size for a FAT32 volume is 4 GiB minus 1 byte (2 32 -1 bytes).
  • - FAT12, FAT16 and FAT32 Windows File System 15 January 2010 7:15 UTC www.dataraid.com [Source type: Reference]

^ File size (32 bits).

^ File size in bytes.
  • DR-DOS System and Programmer's Guide 15 January 2010 7:15 UTC www.drdos.com [Source type: Reference]

.Video applications, large databases, and some other software easily exceed this limit.^ If you are running a very large application, you may need to increase the values of the proc subsystem attributes that control program size limits.
  • Tuning System Resource Allocation 15 January 2010 7:15 UTC h30097.www3.hp.com [Source type: Reference]

^ Some applications like X, Y and Z create files with large amounts of blank space within them.
  • Scalability and Performance in Modern Filesystems 15 January 2010 7:15 UTC oss.sgi.com [Source type: Reference]

^ For these reasons, there may be some compatibility issues when converting old database, or using applications that were written for version 1.8.x or earlier.
  • Chapter 11. System Management and Deployment Issues 15 January 2010 7:15 UTC www.hsqldb.org [Source type: Reference]

.Larger files require another formatting type such as NTFS.^ C:\> chkdsk C: The type of the file system is NTFS. Volume label is OS. WARNING! F parameter not specified.
  • large allocation unit (FAT32/NTFS Clusters) 15 January 2010 7:15 UTC www.computing.net [Source type: FILTERED WITH BAYES]

^ So even not analyzing MFT, we can determine file properties and create friendly file names for such file types.
  • Pandora File Recovery support page. Recover deleted files of any type - free. 15 January 2010 7:15 UTC www.pandorarecovery.com [Source type: Reference]

^ However, such directories cannot be deleted by such types of computers and file systems running on operating systems such as the family of Windows® operating systems produced by Microsoft Corporation for application in desktop computers.
  • Transaction-safe FAT file system - Patent 7174420 15 January 2010 7:15 UTC www.freepatentsonline.com [Source type: Reference]

Fragmentation

.The FAT file system does not contain mechanisms which prevent newly written files from becoming scattered across the partition.^ This is why file system become fragmented.
  • large allocation unit (FAT32/NTFS Clusters) 15 January 2010 7:15 UTC www.computing.net [Source type: FILTERED WITH BAYES]

^ If you dont have a spare hard disk letter, but you have unpartitioned space on your hard disk, create a new partition, set it up as an extended partition and format it as a logical drive with the FAT file system (FAT16 or FAT32).
  • InformIT: Data Protection and Recovery Techniques Part 6: Recovering Data Without Help from the FATLearn how to identify and restore files on a disk with a missing or damaged file allocation table (FAT) > Data Protection and Recovery Techniques Part 6: Recovering Data Without Help from the FAT Learn how to identify and restore files on a disk with a missing or damaged file allocation table (FAT) 15 January 2010 7:15 UTC www.informit.com [Source type: Reference]

^ The most common implementations have a serious drawback in that when files are deleted and new files written to the media, the files fragments tend to become scattered over the entire media making reading and writing a slow process.
  • - FAT12, FAT16 and FAT32 Windows File System 15 January 2010 7:15 UTC www.dataraid.com [Source type: Reference]

[6] .Other file systems, like HPFS, use free space bitmaps that indicate used and available clusters, which could then be quickly looked up in order to find free contiguous areas (improved in exFAT).^ The TFAT file system then finds and allocates a new cluster on disk.
  • Transaction-safe FAT file system - Patent 7174420 15 January 2010 7:15 UTC www.freepatentsonline.com [Source type: Reference]

^ Most file systems use linear bitmap structures to map free versus allocated space.
  • Scalability and Performance in Modern Filesystems 15 January 2010 7:15 UTC oss.sgi.com [Source type: Reference]

^ Indicates a system file.
  • DR-DOS System and Programmer's Guide 15 January 2010 7:15 UTC www.drdos.com [Source type: Reference]

.Another solution is the linkage of all free clusters into one or more lists (as is done in Unix file systems).^ The free callback is also invoked for all entries on the free list when the file is closed.
  • HDF5 Virtual File Layer 15 January 2010 7:15 UTC www.hdfgroup.org [Source type: Reference]

^ These are used by all file systems.
  • Tuning System Resource Allocation 15 January 2010 7:15 UTC h30097.www3.hp.com [Source type: Reference]

^ UNIX file systems.
  • http://www.redhat.com/docs/glossary/index.html 15 January 2010 7:15 UTC www.redhat.com [Source type: Reference]

.Instead, the FAT has to be scanned as an array to find free clusters, which can lead to performance penalties with large disks.^ The TFAT file system then finds and allocates a new cluster on disk.
  • Transaction-safe FAT file system - Patent 7174420 15 January 2010 7:15 UTC www.freepatentsonline.com [Source type: Reference]

^ The point is files get fragmented and file read speed becomes low – while scanning large tables the penalty of locating and opening the file is not huge.
  • MySQL File System Fragmentation Benchmarks | MySQL Performance Blog 15 January 2010 7:15 UTC www.mysqlperformanceblog.com [Source type: FILTERED WITH BAYES]

^ Then, the system will check the FAT entry to find the number of the next cluster, but instead of finding a valid cluster number, it will find a special number like 65,535 (special because it is the largest number you can store in 16 bits).
  • http://euclid.nmu.edu/~randy/Classes/CS426/Notes/FileSystems/vfat-file-system.html 15 January 2010 7:15 UTC euclid.nmu.edu [Source type: Reference]

.In fact, computing free disk space on FAT is one of the most resource intensive operations, as it requires reading the entire FAT linearly.^ Servers require high levels of availability by using multi-pathing solutions, where more than one set of connection hardware exists between the computer and a disk so that if a path fails the system can still access the disk though an alternative path.

^ To provide maximum usable data space on the disk, both internal fragmentation and FAT size must be considered because both consume data area.

^ Most file systems use linear bitmap structures to map free versus allocated space.
  • Scalability and Performance in Modern Filesystems 15 January 2010 7:15 UTC oss.sgi.com [Source type: Reference]

.A possible justification suggested by Microsoft's Raymond Chen for limiting the maximum size of FAT32 partitions created on Windows was the time required to perform a "DIR" operation, which always displays the free disk space as the last line.^ It will vary in size depending on the size of the partition (for FAT32).
  • large allocation unit (FAT32/NTFS Clusters) 15 January 2010 7:15 UTC www.computing.net [Source type: FILTERED WITH BAYES]

^ The E-CDN application requires 2 GB of disk space to operate.
  • Cisco ACNS Software Maintenance and Troubleshooting Guide, Release 4.x - Chapter 2: Cisco ACNS Disk Space Allocation Guidelines  [Cisco Application and Content Networking System (ACNS) Software] - Cisco Systems 15 January 2010 7:15 UTC www.cisco.com [Source type: Reference]

^ As you can see, the maximum partition size under FAT16 is only 2 GB while FAT32 supports up to 32GB. And also, the cluster size for a 2GB partition is 32 KB while a partition between 260 MB to 16 GB ( for home or personal use range ) 's cluster size is 4 KB, saving nearly 8 times less cluster space than a partition that is under FAT16.
  • ActiveWindows -- Frequently Asked Questions - FAT32 ( File AllocationTable 32 ) 15 January 2010 7:15 UTC www.activewin.com [Source type: General]

[18] Displaying this line took longer and longer as the number of clusters increased.
.The High Performance File System (HPFS) divides disk space into bands, which have their own free space bitmap, where multiple files opened for simultaneous write could be expanded separately.^ UFS divides its file systems into cylinder groups.
  • Scalability and Performance in Modern Filesystems 15 January 2010 7:15 UTC oss.sgi.com [Source type: Reference]

^ When a file has been deleted, the disk space occupied by the file can be reused by file system.
  • Pandora File Recovery support page. Recover deleted files of any type - free. 15 January 2010 7:15 UTC www.pandorarecovery.com [Source type: Reference]

^ The enhanced journaled file system (JFS2) segments disk space into blocks .
  • System Management Concepts:Operating System and Devices - File System Types 15 January 2010 7:15 UTC moka.ccr.jussieu.fr [Source type: Reference]

[6]
.Some of the perceived problems with fragmentation resulted from operating system and hardware limitations.^ Some linkers have huge numbers of command line switches, often with provision to continue the command line logically in a file, due to system limits on the length of the actual command line.
  • Storage allocation 15 January 2010 7:15 UTC www.iecc.com [Source type: FILTERED WITH BAYES]

^ The logical sector numbering system usually hides some complexities that must be handled by the disk controller hardware, the disk driver software or both.
  • A Description of the DOS File System 15 January 2010 7:15 UTC alumni.caltech.edu [Source type: Reference]

^ If your operating system has expanded storage, then take advantage of it by allocating a larger SGA despite the resulting paging.

.The single-tasking DOS and the traditionally single-tasking PC hard disk architecture (only 1 outstanding input/output request at a time, no DMA transfers) did not contain mechanisms which could alleviate fragmentation by asynchronously prefetching next data while the application was processing the previous chunks.^ Windows 98 introduced a utility to convert existing hard disks from FAT16 to FAT32 without loss of data.
  • - FAT12, FAT16 and FAT32 Windows File System 15 January 2010 7:15 UTC www.dataraid.com [Source type: Reference]

^ At the time development began, the typical desktop PC would have had disk capacities in the 10s to 100s of megabytes and a server would have been no more than 1 GB. While some thought was given to scaling beyond 32-bit limits, no mechanisms are apparent to manage data effectively in truly huge disk volumes.
  • Scalability and Performance in Modern Filesystems 15 January 2010 7:15 UTC oss.sgi.com [Source type: Reference]

^ The FileInfo entry that previously stored the most recent attribute, date, and time data has its status set to ATDSuperseded.
  • Method and system for file system management using a flash-erasable, programmable, read-only memory - Patent 6256642 15 January 2010 7:15 UTC www.freepatentsonline.com [Source type: Reference]

.Similarly, write-behind caching was often not enabled by default with Microsoft software (if present) given the problem of data loss in case of a crash, made easier by the lack of hardware protection between applications and the system.^ The system then swaps the data between the blocks.
  • Method and system for file system management using a flash-erasable, programmable, read-only memory - Patent 6256642 15 January 2010 7:15 UTC www.freepatentsonline.com [Source type: Reference]

^ This feature minimizes the system overhead caused by read-modify-write operations and is therefore particularly useful for applications that manipulate very large files.
  • C H A P T E R 1 - File System Overview 15 January 2010 7:15 UTC docs.sun.com [Source type: Reference]
  • C H A P T E R 1 - File System Overview 15 January 2010 7:15 UTC docs.sun.com [Source type: Reference]
  • File System Design Basics - SAM-QFS Documentation - wikis.sun.com 15 January 2010 7:15 UTC wikis.sun.com [Source type: Reference]

^ However, such directories cannot be deleted by such types of computers and file systems running on operating systems such as the family of Windows® operating systems produced by Microsoft Corporation for application in desktop computers.
  • Transaction-safe FAT file system - Patent 7174420 15 January 2010 7:15 UTC www.freepatentsonline.com [Source type: Reference]

.MS-DOS also did not offer a system call which would allow applications to make sure a particular file has been completely written to disk in the presence of deferred writes (cf.^ In a file system using striping, file 1 is written to disk 1, disk 2, disk 3, disk 4, and disk 5.
  • C H A P T E R 1 - File System Overview 15 January 2010 7:15 UTC docs.sun.com [Source type: Reference]
  • C H A P T E R 1 - File System Overview 15 January 2010 7:15 UTC docs.sun.com [Source type: Reference]

^ The next file is written to the next logical disk, and so on.
  • File Allocation Methods - SAM-QFS Documentation - wikis.sun.com 15 January 2010 7:15 UTC wikis.sun.com [Source type: Reference]
  • C H A P T E R 1 - File System Overview 15 January 2010 7:15 UTC docs.sun.com [Source type: Reference]
  • C H A P T E R 1 - File System Overview 15 January 2010 7:15 UTC docs.sun.com [Source type: Reference]

^ In the following figure, file 1 is written to disk 1, file 2 is written to disk 2, file 3 is written to disk 3, and so on.
  • C H A P T E R 1 - File System Overview 15 January 2010 7:15 UTC docs.sun.com [Source type: Reference]

fsync in Unix or DosBufReset in OS/2). .Disk caches on MS-DOS were operating on disk block level and were not aware of higher-level structures of the file system.^ Until end of file system - disk blocks.
  • Operating Systems Lecture Notes Lecture 13 File System Implementation 15 January 2010 7:15 UTC people.csail.mit.edu [Source type: Reference]

^ When read a file, put into disk block cache.
  • Operating Systems Lecture Notes Lecture 13 File System Implementation 15 January 2010 7:15 UTC people.csail.mit.edu [Source type: Reference]

^ With disk block caching, physical memory serves as a cache for the files stored on disk.
  • Operating Systems Lecture Notes Lecture 13 File System Implementation 15 January 2010 7:15 UTC people.csail.mit.edu [Source type: Reference]

.In this situation, cheating with regard to the real progress of a disk operation was most dangerous.^ Sun QFS file systems operate most efficiently if the amount of data being written to disk is at least 128 kilobytes.
  • File System Design Basics - SAM-QFS Documentation - wikis.sun.com 15 January 2010 7:15 UTC wikis.sun.com [Source type: Reference]

^ Premature reporting of an out-of-space condition is most likely when operating near disk quota limits or with a nearly full file system.
  • System Management Concepts:Operating System and Devices - File System Types 15 January 2010 7:15 UTC moka.ccr.jussieu.fr [Source type: Reference]

^ Sun StorageTek QFS file systems operate most efficiently if the amount of data being written to disk is at least 128 kilobytes.
  • C H A P T E R 1 - File System Overview 15 January 2010 7:15 UTC docs.sun.com [Source type: Reference]

.Modern operating systems have introduced these optimizations to FAT partitions, but optimizations can still produce unwanted artifacts in case of a system crash.^ The boot partition contains the operating system kernel, as well as critical files needed during the boot process.
  • http://www.redhat.com/docs/glossary/index.html 15 January 2010 7:15 UTC www.redhat.com [Source type: Reference]

^ An FAT file system has FAT12, 16, 32, and uses one of these according to a type of the storage media.
  • METHOD TO DIVIDE A FILE OR MERGE FILES USING FILE ALLOCATION TABLE (FAT) - Patent application 15 January 2010 7:15 UTC www.faqs.org [Source type: Reference]

^ In some cases, the file system can be in such bad shape that the operating system boots into single user mode to allow the user to further the repair process.
  • Anatomy of Linux journaling file systems 15 January 2010 7:15 UTC www.ibm.com [Source type: Academic]

.A Windows NT system will allocate space to files on FAT in advance, selecting large contiguous areas, but in case of a crash, files which were being appended will appear larger than they were ever written into, with dozens of random kilobytes at the end.^ Validates the file space system and its segments.
  • drizzle: plugin/innobase/include/fsp0fsp.h File Reference 15 January 2010 7:15 UTC drizzle.org [Source type: Reference]

^ We see contiguous allocation of space in extents, including the pre-allocation (file extension) of extents at the end of the file.
  • Mapping Database File Objects and Fragmentation - SQLServerCentral 15 January 2010 7:15 UTC www.sqlservercentral.com [Source type: FILTERED WITH BAYES]

^ Can also allocate larger fragments if the end of the file is larger than one eighth of the disk block.
  • Operating Systems Lecture Notes Lecture 13 File System Implementation 15 January 2010 7:15 UTC people.csail.mit.edu [Source type: Reference]

With the large cluster sizes, 16 or 32K, forced by larger FAT32 partitions, the external fragmentation becomes somewhat less significant, and internal fragmentation, i.e. disk space waste (since files are rarely exact multiples of cluster size), starts to be a problem as well, especially when there are a great many small files.

Third party support

.Other IBM PC operating systems—such as Linux, FreeBSD, BeOS and JNode—have all supported FAT, and most added support for VFAT and FAT32 shortly after the corresponding Windows versions were released.^ Linux supports VFAT file access.
  • http://www.redhat.com/docs/glossary/index.html 15 January 2010 7:15 UTC www.redhat.com [Source type: Reference]

^ For all de windows-versions please.
  • max files directories of windows-family : max, directory, files 15 January 2010 7:15 UTC www.experts-exchange.com [Source type: FILTERED WITH BAYES]

^ Linux is one example of an operating system.
  • http://www.redhat.com/docs/glossary/index.html 15 January 2010 7:15 UTC www.redhat.com [Source type: Reference]

.Early Linux distributions also supported a format known as UMSDOS, which was FAT with Unix file attributes (such as long file name and access permissions) stored in a separate file called “--linux-.---”.^ If Long File Name support is available, Long File Name format is used when recovering and saving files with long filenames.
  • Systech Software - Floppy disk recovery, Hard disk recovery - Editor's Choice utilities 15 January 2010 7:15 UTC www.bestdiskrecovery.com [Source type: Reference]

^ Linux supports VFAT file access.
  • http://www.redhat.com/docs/glossary/index.html 15 January 2010 7:15 UTC www.redhat.com [Source type: Reference]

^ Information such as a file name and timestamp are always resident attributes.

.UMSDOS fell into disuse after VFAT was released and is not enabled by default in Linux kernels from version 2.5.7 onwards.^ JFS was first released in 1990, but the current version supported in Linux is the later-developed JFS2.
  • Anatomy of Linux journaling file systems 15 January 2010 7:15 UTC www.ibm.com [Source type: Academic]

^ Kernel-level Internet packet filter subsystem for the 2.4 and higher version of the Linux kernel; Rules can be enabled to allow or deny network connections to the system.
  • http://www.redhat.com/docs/glossary/index.html 15 January 2010 7:15 UTC www.redhat.com [Source type: Reference]

^ UMSDOS was mostly dropped after VFAT was released, although it still remains in the Linux kernel sources.
  • - FAT12, FAT16 and FAT32 Windows File System 15 January 2010 7:15 UTC www.dataraid.com [Source type: Reference]

[21] .The Mac OS X operating system also supports the FAT file systems on volumes other than the boot disk.^ Displays media file system volumes.
  • Cisco ACNS Software Deployment and Configuration Guide, Release 5.0 - Appendix A: Disk Space-Allocation Guidelines  [Cisco Application and Content Networking System (ACNS) Software] - Cisco Systems 15 January 2010 7:15 UTC www.cisco.com [Source type: Reference]
  • Cisco ACNS Software Maintenance and Troubleshooting Guide, Release 4.x - Chapter 2: Cisco ACNS Disk Space Allocation Guidelines  [Cisco Application and Content Networking System (ACNS) Software] - Cisco Systems 15 January 2010 7:15 UTC www.cisco.com [Source type: Reference]

^ OS see operating system ( OS ) .
  • http://www.redhat.com/docs/glossary/index.html 15 January 2010 7:15 UTC www.redhat.com [Source type: Reference]

^ What file systems are supported by Pandora Recovery?
  • Pandora File Recovery support page. Recover deleted files of any type - free. 15 January 2010 7:15 UTC www.pandorarecovery.com [Source type: Reference]

.The Amiga supports FAT through the CrossDOS file system.^ What file systems are supported by Pandora Recovery?
  • Pandora File Recovery support page. Recover deleted files of any type - free. 15 January 2010 7:15 UTC www.pandorarecovery.com [Source type: Reference]

^ The Smart File System (SFS) was developed for the Amiga in 1998, but then released under the GNU Lesser General Public License (LGPL) and supported under Linux in 2005.
  • Anatomy of Linux journaling file systems 15 January 2010 7:15 UTC www.ibm.com [Source type: Academic]

^ By using the vfs/vnode interface, the file system works with the standard Solaris OS kernel and requires no modifications to the kernel for file management support.
  • C H A P T E R 1 - File System Overview 15 January 2010 7:15 UTC docs.sun.com [Source type: Reference]
  • C H A P T E R 1 - File System Overview 15 January 2010 7:15 UTC docs.sun.com [Source type: Reference]

.A free windows based FAT32 formatter is available that overcomes many of the arbitrary limitations imposed by Microsoft.^ You can enable it either by using the Application Verifier , a free download from Microsoft, or by using the Windows D ebugger (Windbg).
  • Mark's Blog 15 January 2010 7:15 UTC blogs.technet.com [Source type: FILTERED WITH BAYES]

^ Once the resident available memory limit is hit, many basic operations begin failing.
  • Mark's Blog 15 January 2010 7:15 UTC blogs.technet.com [Source type: FILTERED WITH BAYES]

^ Like it or not, Microsoft file systems are the lingua franca of file transfer on portable drives these days, merely due to the installed base of Windows computers.
  • Slashdot Ask Slashdot Story | Best Filesystem For External Back-Up Drives? 15 January 2010 7:15 UTC ask.slashdot.org [Source type: General]

[22]

FAT and Alternate Data Streams

.The FAT file system itself is not designed for supporting Alternate Data Streams (ADS), but some operating systems that heavily depend on them have devised various methods for handling them in FAT drives.^ The file system ensures the integrity of the data.
  • Scalability and Performance in Modern Filesystems 15 January 2010 7:15 UTC oss.sgi.com [Source type: Reference]

^ The maximum file system size supported by VxFS depends on the operating system on which it is running.
  • Scalability and Performance in Modern Filesystems 15 January 2010 7:15 UTC oss.sgi.com [Source type: Reference]

^ Scalability also depends on the methods used to organize and access data within the file system.
  • Scalability and Performance in Modern Filesystems 15 January 2010 7:15 UTC oss.sgi.com [Source type: Reference]

.Such methods either store the additional information in extra files and directories (Mac OS), or give new semantics to previously unused fields of the FAT on-disk data structures (OS/2 and Windows NT).^ Every file on the system is stored in a directory.
  • http://euclid.nmu.edu/~randy/Classes/CS426/Notes/FileSystems/vfat-file-system.html 15 January 2010 7:15 UTC euclid.nmu.edu [Source type: Reference]

^ Oracle stores information in memory and on disk.

^ A method of encoding data on the surface of a disk.

.Mac OS using PC Exchange stores its various dates, file attributes and long filenames in a hidden file called FINDER.DAT, and resource forks (a common Mac OS ADS) in a subdirectory called RESOURCE.FRK, in every directory where they are used.^ Every file on the system is stored in a directory.
  • http://euclid.nmu.edu/~randy/Classes/CS426/Notes/FileSystems/vfat-file-system.html 15 January 2010 7:15 UTC euclid.nmu.edu [Source type: Reference]

^ Red Hat Linux uses a hierarchical file system in which files are stored in directories and subdirectories.
  • http://www.redhat.com/docs/glossary/index.html 15 January 2010 7:15 UTC www.redhat.com [Source type: Reference]

^ It can be used from PC, Mac, or Unix platforms.

.From PC Exchange 2.1 onwards, they store the Mac OS long filenames as standard FAT long filenames and convert FAT filenames longer than 31 characters to unique 31-character filenames, which can then be made visible to Macintosh applications.^ X is larger in MDF (32 or 64 filenames, depending on allocation unit size) than in standard FAT 12 (16 filenames), but that's because the clusters are larger, so if you have a LOT of files or a multiple of 64 files, they are all the same.
  • max files directories of windows-family : max, directory, files 15 January 2010 7:15 UTC www.experts-exchange.com [Source type: FILTERED WITH BAYES]

^ File Name and Extension: This is the 11-character name of the file using the conventional 8.3 DOS file naming standard, for example, COMMAND.COM. Note that the "dot" in "COMMAND.COM" is implied and not actually stored on the disk.
  • http://euclid.nmu.edu/~randy/Classes/CS426/Notes/FileSystems/vfat-file-system.html 15 January 2010 7:15 UTC euclid.nmu.edu [Source type: Reference]

^ In other words, they use no more than 32 bits to store the length of the file.
  • Scalability and Performance in Modern Filesystems 15 January 2010 7:15 UTC oss.sgi.com [Source type: Reference]

Mac OS X stores resource forks and metadata (file attributes, other ADS) in a hidden file with a name constructed from the owner filename prefixed with "._", and Finder stores some folder and file metadata in a hidden file called ".DS Store".
.OS/2 heavily depends on extended attributes (EAs) and stores them in a hidden file called "EA DATA. SF" in the root directory of the FAT12 or FAT16 volume.^ Every file on the system is stored in a directory.
  • http://euclid.nmu.edu/~randy/Classes/CS426/Notes/FileSystems/vfat-file-system.html 15 January 2010 7:15 UTC euclid.nmu.edu [Source type: Reference]

^ This is a Directory Table that stores information about the files and directories in the root directory.
  • - FAT12, FAT16 and FAT32 Windows File System 15 January 2010 7:15 UTC www.dataraid.com [Source type: Reference]

^ The number of entries that the root directory can hold depends on the type of volume: .
  • http://euclid.nmu.edu/~randy/Classes/CS426/Notes/FileSystems/vfat-file-system.html 15 January 2010 7:15 UTC euclid.nmu.edu [Source type: Reference]

.This file is indexed by 2 previously reserved bytes in the file's (or directory's) directory entry.^ The name of a directory or file is changed by allocating a new DirEntry or FileEntry, respectively, and then setting the SecondaryPtr of the old entry to point the new entry.
  • Method and system for file system management using a flash-erasable, programmable, read-only memory - Patent 6256642 15 January 2010 7:15 UTC www.freepatentsonline.com [Source type: Reference]

^ Regular directories can have an arbitrary size; they use space on the disk much the way files do, and when more space is needed to hold more entries, the directory can be expanded the same way a file can.
  • http://euclid.nmu.edu/~randy/Classes/CS426/Notes/FileSystems/vfat-file-system.html 15 January 2010 7:15 UTC euclid.nmu.edu [Source type: Reference]

^ Filenames in the directory are first converted to four byte hash values that are used to index the B+ tree.
  • Scalability and Performance in Modern Filesystems 15 January 2010 7:15 UTC oss.sgi.com [Source type: Reference]

.In the FAT32 format, these bytes hold the upper 16 bits of the starting cluster number of the file or directory, hence making it difficult to store EAs on FAT32. Extended attributes are accessible via the Workplace Shell desktop, through REXX scripts, and many system GUI and command-line utilities (such as 4OS2).^ Every file on the system is stored in a directory.
  • http://euclid.nmu.edu/~randy/Classes/CS426/Notes/FileSystems/vfat-file-system.html 15 January 2010 7:15 UTC euclid.nmu.edu [Source type: Reference]

^ A directory within a directory in a hierarchical file system.
  • http://www.redhat.com/docs/glossary/index.html 15 January 2010 7:15 UTC www.redhat.com [Source type: Reference]

^ Can I recover deleted files from the disk formatted using FAT32 file system?
  • Pandora File Recovery support page. Recover deleted files of any type - free. 15 January 2010 7:15 UTC www.pandorarecovery.com [Source type: Reference]

[23]
.To accommodate its OS/2 subsystem, Windows NT supports the handling of extended attributes in HPFS, NTFS, and FAT. It stores EAs on FAT and HPFS using exactly the same scheme as OS/2, but does not support any other kind of ADS as held on NTFS volumes.^ MS/DOS and OS/2 use this scheme.
  • Operating Systems Lecture Notes Lecture 13 File System Implementation 15 January 2010 7:15 UTC people.csail.mit.edu [Source type: Reference]

^ It is commonly confused with LFN support, as almost nobody configured Windows 3.11 to use VFAT and it was automatically enabled (and was also enhanced to support LFNs) in Windows 95.
  • - FAT12, FAT16 and FAT32 Windows File System 15 January 2010 7:15 UTC www.dataraid.com [Source type: Reference]

^ The FAT32 formatting support in Windows 2000 and XP is limited to drives of about 30 gigabytes, which effectively forces users of modern hard drives either to use NTFS or to format the drive using other tools outside Windows.
  • - FAT12, FAT16 and FAT32 Windows File System 15 January 2010 7:15 UTC www.dataraid.com [Source type: Reference]

.Trying to copy a file with any ADS other than EAs from an NTFS volume to a FAT or HPFS volume gives a warning message with the names of the ADSs that will be lost.^ The structure that gives the FAT file system its name is the file allocation table.
  • http://euclid.nmu.edu/~randy/Classes/CS426/Notes/FileSystems/vfat-file-system.html 15 January 2010 7:15 UTC euclid.nmu.edu [Source type: Reference]

^ Remember than FAT-32 doesn't support symbolic links, file ownership, user/group/others access permissions, file name character case (in Microsoft Windows, "Soviet Union" equals to "soviet union"; WILL result in a conflict when copying data from UNIX filesystems!
  • Slashdot Ask Slashdot Story | Best Filesystem For External Back-Up Drives? 15 January 2010 7:15 UTC ask.slashdot.org [Source type: General]

^ FIG. 1B represents just one possible linked list arrangement that represents FIG. 1A. The arrangement would be different if files had been added but then deleted or if the name of a directory was changed.
  • Method and system for file system management using a flash-erasable, programmable, read-only memory - Patent 6256642 15 January 2010 7:15 UTC www.freepatentsonline.com [Source type: Reference]

.Windows 2000 onward acts exactly as Windows NT, except that it ignores EAs when copying to FAT32 without any warning (but shows the warning for other ADSs, like "Macintosh Finder Info" and "Macintosh Resource Fork").^ Windows NT/2000/2003/2008 .

^ What about recovering files from damaged floppy disks on OS's supporting FAT32 file systems like WINDOWS ME, WINDOWS 2000 and WINDOWS XP? .
  • RECOVER Fixed/Floppy Disk v3.0 Release 3 and RECOVER Fixed/Floppy Disk v2.2 - Technical Support Page 15 January 2010 7:15 UTC www.bestdiskrecovery.com [Source type: Reference]

^ The authors would like to add text showing how to do this for other file systems, in particular XFS, and JFS: please email if you can provide this information.

Future

.Microsoft has recently secured patents for VFAT and FAT32 (but not the original FAT).^ Microsoft's patents on FAT are long since expired, and mostly expired on FAT32 too.
  • Microsoft licenses another flash file format | Beyond Binary - CNET News 15 January 2010 7:15 UTC news.cnet.com [Source type: General]

^ Microsoft recently tried to secure existing patents for VFAT and FAT32, which caused concern that they might later seek royalties from Linux distros and from media vendors that pre-format their products (See FAT Licensing below).
  • - FAT12, FAT16 and FAT32 Windows File System 15 January 2010 7:15 UTC www.dataraid.com [Source type: Reference]

^ Like this by ykhan67 December 12, 2009 4:29 PM PST exFAT is the update to FAT32, which was an update to the original FAT (aka FAT16).
  • Microsoft licenses another flash file format | Beyond Binary - CNET News 15 January 2010 7:15 UTC news.cnet.com [Source type: General]

.Despite two earlier rulings against them, Microsoft prevailed and was awarded the patents.^ The patents related to the FAT formats were among those Microsoft included in its suit against TomTom .
  • Microsoft licenses another flash file format | Beyond Binary - CNET News 15 January 2010 7:15 UTC news.cnet.com [Source type: General]

.For most purposes, the NTFS file system is superior to FAT in terms of features and reliability; its main drawbacks are the size overhead for small volumes and the very limited support by anything other than the NT-based versions of Windows, since the exact specification is a trade secret of Microsoft.^ The file system size limitation is the minimum of the following: .
  • System Management Concepts:Operating System and Devices - File System Types 15 January 2010 7:15 UTC moka.ccr.jussieu.fr [Source type: Reference]

^ Displays media file system volumes.
  • Cisco ACNS Software Deployment and Configuration Guide, Release 5.0 - Appendix A: Disk Space-Allocation Guidelines  [Cisco Application and Content Networking System (ACNS) Software] - Cisco Systems 15 January 2010 7:15 UTC www.cisco.com [Source type: Reference]
  • Cisco ACNS Software Maintenance and Troubleshooting Guide, Release 4.x - Chapter 2: Cisco ACNS Disk Space Allocation Guidelines  [Cisco Application and Content Networking System (ACNS) Software] - Cisco Systems 15 January 2010 7:15 UTC www.cisco.com [Source type: Reference]

^ For most purposes, the NTFS file system that was developed for the Windows NT line is superior to FAT from the points of view of efficiency, performance and reliability; its main drawbacks are the size overhead for small volumes and the very limited support by anything other than the NT-based versions of Windows, since the exact specification is a trade secret of Microsoft, which in turn makes it difficult to use a DOS floppy for recovery purposes.
  • - FAT12, FAT16 and FAT32 Windows File System 15 January 2010 7:15 UTC www.dataraid.com [Source type: Reference]

.The availability of NTFS-3G since mid 2006 has led to much improved NTFS support in Unix-like operating systems, considerably alleviating this concern.^ NTFS-3G is also available for Linux.
  • Slashdot Ask Slashdot Story | Best Filesystem For External Back-Up Drives? 15 January 2010 7:15 UTC ask.slashdot.org [Source type: General]

^ In what operating systems NTFS is used?
  • Pandora File Recovery support page. Recover deleted files of any type - free. 15 January 2010 7:15 UTC www.pandorarecovery.com [Source type: Reference]

^ Ext3 file systems add support for journalling to the ext2 file system, which alleviates lengthy file system checks ( fsck ) at bootup after a sudden system crash, reset, or power loss.
  • http://www.redhat.com/docs/glossary/index.html 15 January 2010 7:15 UTC www.redhat.com [Source type: Reference]

.It is still not possible to use NTFS in DOS-like operating systems without third-party drivers, which in turn makes it difficult to use a DOS floppy for recovery purposes.^ In what operating systems NTFS is used?
  • Pandora File Recovery support page. Recover deleted files of any type - free. 15 January 2010 7:15 UTC www.pandorarecovery.com [Source type: Reference]

^ Third-party drivers?
  • Microsoft licenses another flash file format | Beyond Binary - CNET News 15 January 2010 7:15 UTC news.cnet.com [Source type: General]

^ For most purposes, the NTFS file system that was developed for the Windows NT line is superior to FAT from the points of view of efficiency, performance and reliability; its main drawbacks are the size overhead for small volumes and the very limited support by anything other than the NT-based versions of Windows, since the exact specification is a trade secret of Microsoft, which in turn makes it difficult to use a DOS floppy for recovery purposes.
  • - FAT12, FAT16 and FAT32 Windows File System 15 January 2010 7:15 UTC www.dataraid.com [Source type: Reference]

.Microsoft provided a recovery console to work around this issue, but for security reasons it severely limited what could be done through the Recovery Console by default.^ Microsoft provided a recovery console to work around this issue, but they severely limited what could be done through it for "security" reasons.
  • - FAT12, FAT16 and FAT32 Windows File System 15 January 2010 7:15 UTC www.dataraid.com [Source type: Reference]

^ Once the Microsoft Windows Recovery Console is installed, click on Yes, to continue scanning for malware.

^ Please note: If the Microsoft Windows Recovery Console is already installed, ComboFix will continue it's malware removal procedures.

.The movement of recovery utilities to boot CDs based on BartPE or Linux (with NTFS-3G) is finally eroding this drawback.^ NTFS-3G is also available for Linux.
  • Slashdot Ask Slashdot Story | Best Filesystem For External Back-Up Drives? 15 January 2010 7:15 UTC ask.slashdot.org [Source type: General]

^ NTFS-3g [tuxera.com] gives you stable read/write capability on Linux and OS X as a FUSE driver; in fact, many distributions have NTFS-3g in their repositories.
  • Slashdot Ask Slashdot Story | Best Filesystem For External Back-Up Drives? 15 January 2010 7:15 UTC ask.slashdot.org [Source type: General]

^ Recently a commercial company (Tuxera) was formed to provide commercial support for NTFS-3G and provide paid-for version of the driver for MacOS and Linux in addition to the free NTFS-3G. .
  • Slashdot Ask Slashdot Story | Best Filesystem For External Back-Up Drives? 15 January 2010 7:15 UTC ask.slashdot.org [Source type: General]

.FAT is still the normal file system for removable media (with the exception of CDs and DVDs), with FAT12 used on floppies, and FAT16 or FAT32 on most other removable media (such as flash memory cards for digital cameras and USB flash drives).^ Can I recover deleted files from the disk formatted using FAT32 file system?
  • Pandora File Recovery support page. Recover deleted files of any type - free. 15 January 2010 7:15 UTC www.pandorarecovery.com [Source type: Reference]

^ Displays media file system volumes.
  • Cisco ACNS Software Deployment and Configuration Guide, Release 5.0 - Appendix A: Disk Space-Allocation Guidelines  [Cisco Application and Content Networking System (ACNS) Software] - Cisco Systems 15 January 2010 7:15 UTC www.cisco.com [Source type: Reference]
  • Cisco ACNS Software Maintenance and Troubleshooting Guide, Release 4.x - Chapter 2: Cisco ACNS Disk Space Allocation Guidelines  [Cisco Application and Content Networking System (ACNS) Software] - Cisco Systems 15 January 2010 7:15 UTC www.cisco.com [Source type: Reference]

^ In other environments, a system can be disabled by removing its configuration file.
  • Using Default Tools - Database Tables 15 January 2010 7:15 UTC www.hp.com [Source type: Reference]

.Some removable media are not yet large enough to benefit from FAT32 and FAT16 is used on these drives for reasons of compatibility and size overhead, although some larger flash drives, like SDHC, do make use of it.^ You can use this query to decide how much larger to make the shared pool if you are using a multithreaded server.

^ Check these sizes are adequate for your use, and change the column definition as necessary.
  • Chapter 11. System Management and Deployment Issues 15 January 2010 7:15 UTC www.hsqldb.org [Source type: Reference]

^ Like this by ykhan67 December 12, 2009 4:29 PM PST exFAT is the update to FAT32, which was an update to the original FAT (aka FAT16).
  • Microsoft licenses another flash file format | Beyond Binary - CNET News 15 January 2010 7:15 UTC news.cnet.com [Source type: General]

FATX

.FATX is a slightly modified version of the FAT filesystem, and is designed for Microsoft's Xbox video game console hard disk drive and memory cards.^ User can provide adequate disk space for recovered files by installing a second Hard Drive as master / slave drive on the affected computer to recover files from the reformatted Hard Disk.
  • Systech Software - Floppy disk recovery, Hard disk recovery - Editor's Choice utilities 15 January 2010 7:15 UTC www.bestdiskrecovery.com [Source type: Reference]

^ Shorthand for hard disk drive, a hard drive is a device that stores, retrieves, and executes computer data and software.
  • http://www.redhat.com/docs/glossary/index.html 15 January 2010 7:15 UTC www.redhat.com [Source type: Reference]

^ Targets surface damage in system area - excluding Boot Sector of Hard Disk Drive / partition.
  • Systech Software - Floppy disk recovery, Hard disk recovery - Editor's Choice utilities 15 January 2010 7:15 UTC www.bestdiskrecovery.com [Source type: Reference]

FATX is not to be confused with exFAT, described below.

exFAT

exFAT .(also sometimes incorrectly and inappropriately known as FAT64) is an incompatible replacement for FAT file systems that was introduced with Windows Embedded CE 6.0. It is intended to be used on flash drives, where FAT is used today.^ Today, several journaling file systems are actively used.
  • Anatomy of Linux journaling file systems 15 January 2010 7:15 UTC www.ibm.com [Source type: Academic]

^ These are used by all file systems.
  • Tuning System Resource Allocation 15 January 2010 7:15 UTC h30097.www3.hp.com [Source type: Reference]

^ The File System Configuration window appears.
  • Cisco ACNS Software Deployment and Configuration Guide, Release 5.0 - Appendix A: Disk Space-Allocation Guidelines  [Cisco Application and Content Networking System (ACNS) Software] - Cisco Systems 15 January 2010 7:15 UTC www.cisco.com [Source type: Reference]

.Microsoft has offered a hotfix to add support for exFAT to Windows XP,[24] while Windows Vista Service Pack 1 added exFAT support to Windows Vista.^ Windows Vista unterstützt exFAT ab Service Pack 1.
  • Lexikon: File Allocation Table - ComputerBase 15 January 2010 7:15 UTC www.computerbase.de [Source type: Academic]

^ Like this Reply to this comment by ProDigit December 10, 2009 2:23 PM PST XP is a goner, and Vista is outpaced by windows 7, so I think not...
  • Microsoft licenses another flash file format | Beyond Binary - CNET News 15 January 2010 7:15 UTC news.cnet.com [Source type: General]

^ What about recovering files from damaged floppy disks on OS's supporting FAT32 file systems like WINDOWS ME, WINDOWS 2000 and WINDOWS XP? .
  • RECOVER Fixed/Floppy Disk v3.0 Release 3 and RECOVER Fixed/Floppy Disk v2.2 - Technical Support Page 15 January 2010 7:15 UTC www.bestdiskrecovery.com [Source type: Reference]

[25] exFAT introduces a free space bitmap allowing faster space allocation and faster deletes, support for files up to .264 bytes (16777216 TB), larger cluster sizes (up to 32 MB in the first implementation), an extensible directory structure and name hashes for filenames for faster comparisons.^ Larger directories use a B+ tree keyed on name for faster retrieval.

^ In one embodiment of a TFAT volume, when a first cluster is allocated for a new directory or subdirectory, only two DIRENTRYs (‘.’ and ‘..’ entries) are written when the new directory or subdirectory is created (block 310 ).
  • Transaction-safe FAT file system - Patent 7174420 15 January 2010 7:15 UTC www.freepatentsonline.com [Source type: Reference]

^ My code looks for an exact-sized hole first, then a hole one block larger than required, then two blocks, and so on.
  • View topic - DynAlloc - Dynamic Memory Allocation :: AVR Freaks 15 January 2010 7:15 UTC www.avrfreaks.net [Source type: General]

It does not have short 8.3 filenames anymore. .It does not appear to have security ACLs or file system journaling like NTFS, though device manufacturers can choose to implement simplified support for transactions (backup file allocation table used for the write operations, primary FAT for storing last known good allocation table).^ Today, several journaling file systems are actively used.
  • Anatomy of Linux journaling file systems 15 January 2010 7:15 UTC www.ibm.com [Source type: Academic]

^ The log file is used to recover an NTFS volume after a system failure.

^ TABLE 1-6 shows the default file allocation methods used.
  • C H A P T E R 1 - File System Overview 15 January 2010 7:15 UTC docs.sun.com [Source type: Reference]

TFAT/TexFAT

.TFAT and TexFAT are layers over the FAT and exFAT file systems respectively that provide a level of transaction safety to reduce the risk of data loss in the event of a power outage or unexpected removal of the drive.^ The file system ensures the integrity of the data.
  • Scalability and Performance in Modern Filesystems 15 January 2010 7:15 UTC oss.sgi.com [Source type: Reference]

^ A transaction-safe FAT file system is described.
  • Transaction-safe FAT file system - Patent 7174420 15 January 2010 7:15 UTC www.freepatentsonline.com [Source type: Reference]

^ FAT file systems by design are not transaction-safe file systems.
  • Transaction-safe FAT file system - Patent 7174420 15 January 2010 7:15 UTC www.freepatentsonline.com [Source type: Reference]

Design

Overview

The following is an overview of the order of structures in a FAT partition or disk:
Contents Boot
Sector
FS Information
Sector
(FAT32 only)
More reserved
sectors
(optional)
File
Allocation
Table #1
File
Allocation
Table #2
Root
Directory
(FAT12/16 only)
Data Region (for files and directories) ...
(To end of partition or disk)
Size in sectors (number of reserved sectors) (number of FATs)*(sectors per FAT) (number of root entries*32)/Bytes per sector NumberOfClusters*SectorsPerCluster
.A FAT file system is composed of four different sections.^ Understanding File System Options Whether you're looking for a refresher on files systems or want to learn the difference between FAT file systems vs. NTFS file systems, this tutorial explains the ins and outs, and pros and cons of each.
  • file allocation table definition - Wi-FiPlanet.com 15 January 2010 7:15 UTC wi-fiplanet.webopedia.com [Source type: General]

^ It is possible to build a file system with mismatched striped groups, which are multiple striped groups with different numbers of devices in each group.
  • C H A P T E R 1 - File System Overview 15 January 2010 7:15 UTC docs.sun.com [Source type: Reference]

^ The following sections describe these file systems.
  • System Management Concepts:Operating System and Devices - File System Types 15 January 2010 7:15 UTC moka.ccr.jussieu.fr [Source type: Reference]

.
  1. The Reserved sectors, located at the very beginning.^ Before putting a Root folder back on its original location, you need to calculate the number of sectors originally reserved for the folder.
    • RECOVER Fixed/Floppy Disk v3.0 Release 3 and RECOVER Fixed/Floppy Disk v2.2 - Technical Support Page 15 January 2010 7:15 UTC www.bestdiskrecovery.com [Source type: Reference]

    ^ Putting a Subfolder back on its original location Before putting a subfolder back on its original location, you need to calculate the number of sectors originally reserved for the subfolder.
    • RECOVER Fixed/Floppy Disk v3.0 Release 3 and RECOVER Fixed/Floppy Disk v2.2 - Technical Support Page 15 January 2010 7:15 UTC www.bestdiskrecovery.com [Source type: Reference]

    ^ Because the loader is usually very simple, only one sector is normally reserved.

    .The first reserved sector (sector 0) is the Boot Sector (aka Partition Boot Record).^ MBR ) The first sector of a hard drive; generally contains the boot loader , which starts an operating system.
    • http://www.redhat.com/docs/glossary/index.html 15 January 2010 7:15 UTC www.redhat.com [Source type: Reference]

    ^ If you like INT 25H interpretation, the Boot Sector for a floppy disk is its very first Sector, that is Sector 0.
    • RECOVER Fixed/Floppy Disk v3.0 Release 3 and RECOVER Fixed/Floppy Disk v2.2 - Technical Support Page 15 January 2010 7:15 UTC www.bestdiskrecovery.com [Source type: Reference]

    ^ The data segment location for both MFT and the backup MFT, $Mft and $MftMirr respectively, are recorded in the boot sector.

    .It includes an area called the BIOS Parameter Block (with some basic file system information, in particular its type, and pointers to the location of the other sections) and usually contains the operating system's boot loader code.^ A string describing the operating system type.
    • Using Default Tools - Database Tables 15 January 2010 7:15 UTC www.hp.com [Source type: Reference]

    ^ The tip contains information about what percent of the file is overwritten by other files.
    • Pandora File Recovery support page. Recover deleted files of any type - free. 15 January 2010 7:15 UTC www.pandorarecovery.com [Source type: Reference]

    ^ A unique file containing a password or other authentication information.
    • http://www.redhat.com/docs/glossary/index.html 15 January 2010 7:15 UTC www.redhat.com [Source type: Reference]

    .The total count of reserved sectors is indicated by a field inside the Boot Sector.^ In one embodiment, the variable corresponds to a number of FATs (NOF) field located in the boot sector of the volume.
    • Transaction-safe FAT file system - Patent 7174420 15 January 2010 7:15 UTC www.freepatentsonline.com [Source type: Reference]

    ^ The process of claim 1, wherein setting and resetting the variable comprises setting and resetting a number of FATS field in a boot sector of the storage medium.
    • Transaction-safe FAT file system - Patent 7174420 15 January 2010 7:15 UTC www.freepatentsonline.com [Source type: Reference]

    .Important information from the Boot Sector is accessible through an operating system structure called the Drive Parameter Block in DOS and OS/2. For FAT32 file systems, the reserved sectors include a File System Information Sector at sector 1 and a Backup Boot Sector at Sector 6.
  2. The FAT Region.^ OS see operating system ( OS ) .
    • http://www.redhat.com/docs/glossary/index.html 15 January 2010 7:15 UTC www.redhat.com [Source type: Reference]

    ^ This includes protection information and the file type.
    • Operating Systems Lecture Notes Lecture 13 File System Implementation 15 January 2010 7:15 UTC people.csail.mit.edu [Source type: Reference]

    ^ Exact location of Boot Sector depends on other drive parameters.
    • RECOVER Fixed/Floppy Disk v3.0 Release 3 and RECOVER Fixed/Floppy Disk v2.2 - Technical Support Page 15 January 2010 7:15 UTC www.bestdiskrecovery.com [Source type: Reference]

    .This typically contains two copies (may vary) of the File Allocation Table for the sake of redundancy checking, although the extra copy is rarely used, even by disk repair utilities.^ Extent Allocation A disk space allocation method in which extents of variable size are allocated to a file.
    • Scalability and Performance in Modern Filesystems 15 January 2010 7:15 UTC oss.sgi.com [Source type: Reference]

    ^ TABLE 1-6 shows the default file allocation methods used.
    • C H A P T E R 1 - File System Overview 15 January 2010 7:15 UTC docs.sun.com [Source type: Reference]

    ^ File fragmentation detail is usually stored in the File Allocation Table (two copies of them are there).
    • RECOVER Fixed/Floppy Disk v3.0 Release 3 and RECOVER Fixed/Floppy Disk v2.2 - Technical Support Page 15 January 2010 7:15 UTC www.bestdiskrecovery.com [Source type: Reference]

    .These are maps of the Data Region, indicating which clusters are used by files and directories.
  3. The Root Directory Region.^ But I'd like to minimize these issues by using a filesystem that has the best multi-OS support for both reading and writing, while at the same time supporting large files."
    • Slashdot Ask Slashdot Story | Best Filesystem For External Back-Up Drives? 15 January 2010 7:15 UTC ask.slashdot.org [Source type: General]

    ^ When a backed-up directory structure (for ROOT Folder / Subfolder) is used to recover files, you doesn't have to remember any directory path so as to reach any folder and recover files in it.
    • Systech Software - Floppy disk recovery, Hard disk recovery - Editor's Choice utilities 15 January 2010 7:15 UTC www.bestdiskrecovery.com [Source type: Reference]

    ^ It can't use the file name information from MFT. Howerer, several file types, for example MP3 files or Microsoft Office Documents, store some file information inside of file data stream.
    • Pandora File Recovery support page. Recover deleted files of any type - free. 15 January 2010 7:15 UTC www.pandorarecovery.com [Source type: Reference]

    .This is a Directory Table that stores information about the files and directories located in the root directory.^ Metadata Information about the files stored in the file system.
    • Scalability and Performance in Modern Filesystems 15 January 2010 7:15 UTC oss.sgi.com [Source type: Reference]

    ^ What is in an inode - information about a file.
    • Operating Systems Lecture Notes Lecture 13 File System Implementation 15 January 2010 7:15 UTC people.csail.mit.edu [Source type: Reference]

    ^ DIRENTRY contains information about a file or directory, and directories are composed of DIRENTRY structures.
    • Transaction-safe FAT file system - Patent 7174420 15 January 2010 7:15 UTC www.freepatentsonline.com [Source type: Reference]

    .It is only used with FAT12 and FAT16, and imposes on the root directory a fixed maximum size which is pre-allocated at creation of this volume.^ In one embodiment of a TFAT volume, when a first cluster is allocated for a new directory or subdirectory, only two DIRENTRYs (‘.’ and ‘..’ entries) are written when the new directory or subdirectory is created (block 310 ).
    • Transaction-safe FAT file system - Patent 7174420 15 January 2010 7:15 UTC www.freepatentsonline.com [Source type: Reference]

    ^ The root extent of the map is called btree and the leaf extents are called xtree s (and contain an array of entries called xad s) if they are for an allocation map, and dtree s if they are for a directory map.

    ^ The XFS file system has been designed from scratch to scale to previously unheard of levels in terms of file system size, maximum file size, number of files, and directory size.
    • Scalability and Performance in Modern Filesystems 15 January 2010 7:15 UTC oss.sgi.com [Source type: Reference]

    .FAT32 stores the root directory in the Data Region, along with files and other directories, allowing it to grow without such a constraint.^ The type is 1 for directory, 2 for file or 5 for the Root Entry.
    • POIFS File System Internals 15 January 2010 7:15 UTC poi.apache.org [Source type: Reference]

    ^ This cache stores the directory lookup information for files whose paths are short (30 characters or less), removing the need for directory lookups to be performed on the fly.
    • C H A P T E R 1 - File System Overview 15 January 2010 7:15 UTC docs.sun.com [Source type: Reference]
    • C H A P T E R 1 - File System Overview 15 January 2010 7:15 UTC docs.sun.com [Source type: Reference]

    ^ Oh, and NTFS does more reads and writes on a drive per unit of stored data, so NTFS formated flash drives would fail sooner than under FAT32 or a Flash optimized file format system.
    • Microsoft licenses another flash file format | Beyond Binary - CNET News 15 January 2010 7:15 UTC news.cnet.com [Source type: General]

    .Thus, for FAT32, the Data Region starts here.
  4. The Data Region.^ In block 2905, the system sets the variables Offset and Len and writes the data to a data region starting at the first location in free space.
    • Method and system for file system management using a flash-erasable, programmable, read-only memory - Patent 6256642 15 January 2010 7:15 UTC www.freepatentsonline.com [Source type: Reference]

    .This is where the actual file and directory data is stored and takes up most of the partition.^ The .backup file can be up to the size of the *.data file.
    • Chapter 11. System Management and Deployment Issues 15 January 2010 7:15 UTC www.hsqldb.org [Source type: Reference]

    ^ This cache stores the directory lookup information for files whose paths are short (30 characters or less), removing the need for directory lookups to be performed on the fly.
    • C H A P T E R 1 - File System Overview 15 January 2010 7:15 UTC docs.sun.com [Source type: Reference]

    ^ File System The software used to organize and manage the data stored on disk drives.
    • Scalability and Performance in Modern Filesystems 15 January 2010 7:15 UTC oss.sgi.com [Source type: Reference]

    .The size of files and subdirectories can be increased arbitrarily (as long as there are free clusters) by simply adding more links to the file's chain in the FAT. Note however, that files are allocated in units of clusters, so if a 1 KB file resides in a 32 KB cluster, 31 KB are wasted.^ The more the number of sectors in a cluster (allocation unit), the lesser the files get fragmented.
    • RECOVER Fixed/Floppy Disk v3.0 Release 3 and RECOVER Fixed/Floppy Disk v2.2 - Technical Support Page 15 January 2010 7:15 UTC www.bestdiskrecovery.com [Source type: Reference]

    ^ Files also get 64 sectors in each cluster allocated to them.
    • RECOVER Fixed/Floppy Disk v3.0 Release 3 and RECOVER Fixed/Floppy Disk v2.2 - Technical Support Page 15 January 2010 7:15 UTC www.bestdiskrecovery.com [Source type: Reference]

    ^ However, for any given disk size, the smaller the unit, the more there must be.

    FAT32 typically commences the Root Directory Table in cluster number 2: the first cluster of the Data Region.
.FAT uses little endian format for entries in the header and the FAT(s).^ No, you can not open contents of grayed disc drives because they are formatted using file system other than NTFS, FAT or FAT32.
  • Pandora File Recovery support page. Recover deleted files of any type - free. 15 January 2010 7:15 UTC www.pandorarecovery.com [Source type: Reference]

^ When this bit is set, TFAT uses the second cluster entry in FAT 0 for last known good FAT determination.
  • Transaction-safe FAT file system - Patent 7174420 15 January 2010 7:15 UTC www.freepatentsonline.com [Source type: Reference]

Boot Sector

.It is important to note that the first sector on a device isn't necessarily the boot sector.^ Remember that the first sector ( sector 1 on track 0, side 0 ) on a floppy disk is the Boot Sector.
  • RECOVER Fixed/Floppy Disk v3.0 Release 3 and RECOVER Fixed/Floppy Disk v2.2 - Technical Support Page 15 January 2010 7:15 UTC www.bestdiskrecovery.com [Source type: Reference]

^ On floppy disks, the first FAT (File Allocation Table) immediately follows the boot sector.
  • RECOVER Fixed/Floppy Disk v3.0 Release 3 and RECOVER Fixed/Floppy Disk v2.2 - Technical Support Page 15 January 2010 7:15 UTC www.bestdiskrecovery.com [Source type: Reference]

^ Recovers files from disks which have bad sectors in FAT.If Boot Sector or first FAT Sector of floppy disk is damaged, buy one of the commercial disk utilities.
  • Systech Software - Floppy disk recovery, Hard disk recovery - Editor's Choice utilities 15 January 2010 7:15 UTC www.bestdiskrecovery.com [Source type: Reference]

.For partitioned devices (such as hard drives), the first sector is the Master Boot Record.^ On a Hard Disk Drive, Sector 0 is the Boot Sector (again INT 25H interpretation), but the Boot Sector is not the very first Sector on disk.
  • RECOVER Fixed/Floppy Disk v3.0 Release 3 and RECOVER Fixed/Floppy Disk v2.2 - Technical Support Page 15 January 2010 7:15 UTC www.bestdiskrecovery.com [Source type: Reference]

^ Not for Hard Disk Drives with bad Boot sector (not a feature!
  • Systech Software - Floppy disk recovery, Hard disk recovery - Editor's Choice utilities 15 January 2010 7:15 UTC www.bestdiskrecovery.com [Source type: Reference]

^ On a Hard Disk Drive, the Boot Sector is not the first sector because Master Boot Record has to be there.
  • RECOVER Fixed/Floppy Disk v3.0 Release 3 and RECOVER Fixed/Floppy Disk v2.2 - Technical Support Page 15 January 2010 7:15 UTC www.bestdiskrecovery.com [Source type: Reference]

On un-partitioned devices (eg. floppy disk) the first sector is the .Volume Boot Record.^ Volume Boot Record (FAT12 & FAT16) The Volume Boot Record (referred to as the Boot Record) contains more of the volume specific information required to locate information on the device.
  • An #127 - FAT16 File System Driver for CompactFlash - MCS Electronics 15 January 2010 7:15 UTC www.mcselec.com [Source type: Reference]

^ Once the driver know where the first volume starts on the device (which sector to start reading) we can obtain the location of the Volume Boot Record.
  • An #127 - FAT16 File System Driver for CompactFlash - MCS Electronics 15 January 2010 7:15 UTC www.mcselec.com [Source type: Reference]

Common structure of the first 36 bytes used by all FAT versions:
Byte Offset Length (bytes) Description
0x00 3 Jump instruction. This instruction will be executed and will skip past the rest of the (non-executable) header if the partition is booted from. See .Volume Boot Record.^ Volume Boot Record (FAT12 & FAT16) The Volume Boot Record (referred to as the Boot Record) contains more of the volume specific information required to locate information on the device.
  • An #127 - FAT16 File System Driver for CompactFlash - MCS Electronics 15 January 2010 7:15 UTC www.mcselec.com [Source type: Reference]

^ Once the driver know where the first volume starts on the device (which sector to start reading) we can obtain the location of the Volume Boot Record.
  • An #127 - FAT16 File System Driver for CompactFlash - MCS Electronics 15 January 2010 7:15 UTC www.mcselec.com [Source type: Reference]

If the jump is two-byte near jmp it is followed by a NOP instruction.
0x03 8 OEM Name (padded with spaces). This value determines in which system disk was formatted. MS-DOS checks this field to determine which other parts of the boot record can be relied on.[26][27] Common values are IBM  3.3 (with two spaces between the "IBM" and the "3.3"), MSDOS5.0, MSWIN4.1 and mkdosfs.
0x0b 2 Bytes per sector. A common value is 512, especially for file systems on IDE (or compatible) disks. The BIOS Parameter Block starts here.
0x0d 1 Sectors per cluster. Allowed values are powers of two from 1 to 128. However, the value must not be such that the number of bytes per cluster becomes greater than 32 KB.
0x0e 2 Reserved sector count. The number of sectors before the first FAT in the file system image. Should be 1 for FAT12/FAT16. Usually 32 for FAT32.
0x10 1 Number of file allocation tables. Almost always 2.
0x11 2 Maximum number of root directory entries. Only used on FAT12 and FAT16, where the root directory is handled specially. Should be 0 for FAT32. This value should always be such that the root directory ends on a sector boundary (i.e. such that its size becomes a multiple of the sector size). 224 is typical for floppy disks.
0x13 2 Total sectors (if zero, use 4 byte value at offset 0x20)
0x15 1 Media descriptor[28]
0xF0 3.5" Double Sided, 80 tracks per side, 18 or 36 sectors per track (1.44MB or 2.88MB). 5.25" Double Sided, 80 tracks per side, 15 sectors per track (1.2MB). Used also for other media types.
0xF8 Fixed disk (i.e. Hard disk).[29]
0xF9 3.5" Double sided, 80 tracks per side, 9 sectors per track (720K). 5.25" Double sided, 80 tracks per side, 15 sectors per track (1.2MB)
0xFA 5.25" Single sided, 80 tracks per side, 8 sectors per track (320K)
0xFB 3.5" Double sided, 80 tracks per side, 8 sectors per track (640K)
0xFC 5.25" Single sided, 40 tracks per side, 9 sectors per track (180K)
0xFD 5.25" Double sided, 40 tracks per side, 9 sectors per track (360K). Also used for 8".
0xFE 5.25" Single sided, 40 tracks per side, 8 sectors per track (160K). Also used for 8".
0xFF 5.25" Double sided, 40 tracks per side, 8 sectors per track (320K)
.Same value of media descriptor should be repeated as first byte of each copy of FAT. Certain operating systems (MSX-DOS version 1.0) ignore boot sector parameters altogether and use media descriptor value from the first byte of FAT to determine file system parameters.^ Use abstractions for file descriptors .
  • Framework Design Rules 15 January 2010 7:15 UTC www.cs.wustl.edu [Source type: Reference]

^ The first sector is copied last.
  • Transaction-safe FAT file system - Patent 7174420 15 January 2010 7:15 UTC www.freepatentsonline.com [Source type: Reference]

^ The maximum value for this parameter depends on your operating system.

0x16 2 Sectors per File Allocation Table for FAT12/FAT16
0x18 2 Sectors per track
0x1a 2 Number of heads
0x1c 4 Count of hidden sectors preceding the partition that contains this FAT volume. This field should always be zero on media that are not partitioned.
0x20 4 Total sectors (if greater than 65535; otherwise, see offset 0x13)

Extended BIOS Parameter Block

Further structure used by FAT12 and FAT16, also known as Extended BIOS Parameter Block:
Byte Offset Length (bytes) Description
0x24 1 Physical drive number (0x00 for removable media, 0x80 for hard disks)
0x25 1 Reserved ("current head")
In Windows NT bit 0 is a dirty flag to request chkdsk at boot time. bit 1 requests surface scan too.[29]
0x26 1 Extended boot signature. (Should be 0x29[28]. Indicates that the following 3 entries exist.)
0x27 4 ID (serial number)
0x2b 11 Volume Label, padded with blanks (0x20).
0x36 8 FAT file system type, padded with blanks (0x20), e.g.: "FAT12   ", "FAT16   ". This is not meant to be used to determine drive type, however, some utilities use it in this way.
0x3e 448 Operating system boot code
0x1FE 2 Boot sector signature (0x55 0xAA)
The boot sector is portrayed here as found on e.g. an OS/2 1.3 boot diskette. .Earlier versions used a shorter BIOS Parameter Block and their boot code would start earlier (for example at offset 0x2b in OS/2 1.1).^ In order to understand the version store, let me start with an example.
  • SQL Server Storage Engine 15 January 2010 7:15 UTC blogs.msdn.com [Source type: FILTERED WITH BAYES]

^ Starting with SQL Server 2005, the trigger implementation was changed to use row versions.
  • SQL Server Storage Engine 15 January 2010 7:15 UTC blogs.msdn.com [Source type: FILTERED WITH BAYES]

^ Each extent is described by its block offset within the file, its length in blocks, and its starting block in the file system.
  • Scalability and Performance in Modern Filesystems 15 January 2010 7:15 UTC oss.sgi.com [Source type: Reference]

Further structure used by FAT32:
Byte Offset Length (bytes) Description
0x24 4 Sectors per file allocation table
0x28 2 FAT Flags (Only used during a conversion from a FAT12/16 volume.)
0x2a 2 Version (Defined as 0)
0x2c 4 Cluster number of root directory start
0x30 2 Sector number of FS Information Sector
0x32 2 Sector number of a copy of this boot sector (0 if no backup copy exists)
0x34 12 Reserved
0x40 1 Physical Drive Number (see FAT12/16 BPB at offset 0x24)
0x41 1 Reserved (see FAT12/16 BPB at offset 0x25)
0x42 1 Extended boot signature. (see FAT12/16 BPB at offset 0x26)
0x43 4 ID (serial number)
0x47 11 Volume Label
0x52 8 FAT file system type: "FAT32   "
0x5a 420 Operating system boot code
0x1FE 2 Boot sector signature (0x55 0xAA)

Exceptions

.The implementation of FAT used in MS-DOS for the Apricot PC had a different boot sector layout, to accommodate that computer's non-IBM compatible BIOS. The jump instruction and OEM name were omitted, and the MS-DOS file system parameters (offsets 0x0B - 0x17 in the standard sector) were located at offset 0x50. Later versions of Apricot MS-DOS gained the ability to read and write disks with the standard boot sector in addition to those with the Apricot one.^ In addition to storing the information, the computer system will typically read, modify, and delete the information in the files.
  • Method and system for file system management using a flash-erasable, programmable, read-only memory - Patent 6256642 15 January 2010 7:15 UTC www.freepatentsonline.com [Source type: Reference]

^ Allocation Increments for ms File Systems .
  • C H A P T E R 1 - File System Overview 15 January 2010 7:15 UTC docs.sun.com [Source type: Reference]

^ One such file system was developed by Microsoft Corporation for its Disk Operating System (MS-DOS).
  • Method and system for file system management using a flash-erasable, programmable, read-only memory - Patent 6256642 15 January 2010 7:15 UTC www.freepatentsonline.com [Source type: Reference]

.DOS Plus on the BBC Master 512 did not use conventional boot sectors at all.^ Master File Table The table that keeps track of all allocated files in NTFS. The Master File Table (MFT) takes the place of the inodes typically used in Unix file system implementations.
  • Scalability and Performance in Modern Filesystems 15 January 2010 7:15 UTC oss.sgi.com [Source type: Reference]

^ Boot.ini: adding /3G option (this did not change my results at all, still have a barrier) .
  • Mark's Blog : Pushing the Limits of Windows: Virtual Memory 15 January 2010 7:15 UTC blogs.technet.com [Source type: FILTERED WITH BAYES]

.Data disks omitted the boot sector and began with a single copy of the FAT (the first byte of the FAT was used to determine disk capacity) while boot disks began with a miniature ADFS file system containing the boot loader, followed by a single FAT. It could also access standard PC disks formatted to 180 KB or 360 KB, again using the first byte of the FAT to determine the capacity.^ File System The software used to organize and manage the data stored on disk drives.
  • Scalability and Performance in Modern Filesystems 15 January 2010 7:15 UTC oss.sgi.com [Source type: Reference]

^ A piece of data stored as a single addressable object on a file system.
  • http://www.redhat.com/docs/glossary/index.html 15 January 2010 7:15 UTC www.redhat.com [Source type: Reference]

^ The file system ensures the integrity of the data.
  • Scalability and Performance in Modern Filesystems 15 January 2010 7:15 UTC oss.sgi.com [Source type: Reference]

FS Information Sector

.The "FS Information Sector" was introduced in FAT32[30] for speeding up access times of certain operations (in particular, getting the amount of free space).^ Value limits set to manage access to system and network resources or the amount of storage used by a particular user or group.
  • http://www.redhat.com/docs/glossary/index.html 15 January 2010 7:15 UTC www.redhat.com [Source type: Reference]

^ Because the inode space (which holds information about the files) is dynamically allocated, the maximum number of files is limited only by the amount of disk storage available.
  • C H A P T E R 1 - File System Overview 15 January 2010 7:15 UTC docs.sun.com [Source type: Reference]

^ Many operating systems page and swap to accommodate large amounts of information that do not fit into real memory.

.It is located at a sector number specified in the boot record at position 0x30 (usually sector 1, immediately after the boot record).^ To enable caching of session cursors, you must set the initialization parameter SESSION_CACHED_CURSORS. The value of this parameter is a positive integer specifying the maximum number of session cursors kept in the cache.

^ The value of this parameter is a positive integer specifying the maximum number of session cursors kept in the cache.

Byte Offset Length (bytes) Description
0x00 4 FS information sector signature (0x52 0x52 0x61 0x41 / "RRaA")
0x04 480 Reserved (byte values are 0x00)
0x1e4 4 FS information sector signature (0x72 0x72 0x41 0x61 / "rrAa")
0x1e8 4 Number of free clusters on the drive, or -1 if unknown
0x1ec 4 Number of the most recently allocated cluster
0x1f0 14 Reserved (byte values are 0x00)
0x1fe 2 FS information sector signature (0x55 0xAA)

File Allocation Table

.A partition is divided up into identically sized clusters, small blocks of contiguous space.^ Blocks are numbered such that a small number are used from each disk or partition in succession.
  • Scalability and Performance in Modern Filesystems 15 January 2010 7:15 UTC oss.sgi.com [Source type: Reference]

^ Illustration of UFS direct and indirect block pointers UFS uses traditional bitmaps to keep track of free space, and in general the block size used is fixed by the implementation.
  • Scalability and Performance in Modern Filesystems 15 January 2010 7:15 UTC oss.sgi.com [Source type: Reference]

^ A single extent can consist of up to two million contiguous blocks or a maximum of 4GB of disk space.
  • Scalability and Performance in Modern Filesystems 15 January 2010 7:15 UTC oss.sgi.com [Source type: Reference]

.Cluster sizes vary depending on the type of FAT file system being used and the size of the partition, typically cluster sizes lie somewhere between 2 KB and 32 KB. Each file may occupy one or more of these clusters depending on its size; thus, a file is represented by a chain of these clusters (referred to as a singly linked list).^ The file system uses handles as described above as pointers in the linked lists.
  • Method and system for file system management using a flash-erasable, programmable, read-only memory - Patent 6256642 15 January 2010 7:15 UTC www.freepatentsonline.com [Source type: Reference]

^ Metadata allocation varies according to the type of file system you have: .
  • C H A P T E R 1 - File System Overview 15 January 2010 7:15 UTC docs.sun.com [Source type: Reference]

^ The total size of the File System in bytes.
  • Using Default Tools - Database Tables 15 January 2010 7:15 UTC www.hp.com [Source type: Reference]

.However these clusters are not necessarily stored adjacent to one another on the disk's surface but are often instead fragmented throughout the Data Region.^ During reclamation, the data in a superseded entry is ignored because another entry(ies) points to the data region.
  • Method and system for file system management using a flash-erasable, programmable, read-only memory - Patent 6256642 15 January 2010 7:15 UTC www.freepatentsonline.com [Source type: Reference]

^ If the data is moved, then the new data can be integrated with the old data and written to one region in the new block with only one FileInfo record.
  • Method and system for file system management using a flash-erasable, programmable, read-only memory - Patent 6256642 15 January 2010 7:15 UTC www.freepatentsonline.com [Source type: Reference]

^ When a process commits a region of virtual memory, the operating system guarantees that it can maintain all the data the process stores in the memory either in physical memory or on disk.
  • Mark's Blog : Pushing the Limits of Windows: Virtual Memory 15 January 2010 7:15 UTC blogs.technet.com [Source type: FILTERED WITH BAYES]
  • Mark's Blog 15 January 2010 7:15 UTC blogs.technet.com [Source type: FILTERED WITH BAYES]

.The File Allocation Table (FAT) is a list of entries that map to each cluster on the partition.^ Each file in NTFS is mapped by an entry in the master file table or MFT. .
  • Scalability and Performance in Modern Filesystems 15 January 2010 7:15 UTC oss.sgi.com [Source type: Reference]

^ Number 2 is the block allocation map file.

^ Filesets are defined as and by a fileset inode table , which is an inode allocation map file.

Each entry records one of five things:
  • the cluster number of the next cluster in a chain
  • a special end of clusterchain (EOC) entry that indicates the end of a chain
  • a special entry to mark a bad cluster
  • a special entry to mark a reserved cluster[citation needed]
  • a zero to note that the cluster is unused
.Each version of the FAT file system uses a different size for FAT entries.^ It is also advantageous to control the block size used by the file system.
  • Scalability and Performance in Modern Filesystems 15 January 2010 7:15 UTC oss.sgi.com [Source type: Reference]

^ FAT File System Disk Volume Structures Describes the disk volume structures used in the FAT file system.
  • file allocation table definition - Wi-FiPlanet.com 15 January 2010 7:15 UTC wi-fiplanet.webopedia.com [Source type: General]

^ File Systems (FAT, HPFS, NTFS) Contains brief technical descriptions of the FAT file system, VFAT, HPFS, and NTFS. FAT types and cluster sizes This Microsoft Knowledge Base article discusses FAT types and cluster size and their relation to logical drive size, including information on double-spaced drives.
  • file allocation table definition - Wi-FiPlanet.com 15 January 2010 7:15 UTC wi-fiplanet.webopedia.com [Source type: General]

.Smaller numbers result in a smaller FAT table, but waste space in large partitions by needing to allocate in large clusters.^ If number of pages in an object is 8 or larges, its pages are allocated from uniform extents.
  • SQL Server Storage Engine 15 January 2010 7:15 UTC blogs.msdn.com [Source type: FILTERED WITH BAYES]

^ We've all got to know and hate this problem from FAT (cluster size of 32K leads to massive waste of space, in some cases over 50%).

^ A segment is a set of extents that have been allocated for a specific type of database object such as a table, index, cluster.

.The FAT12 file system uses 12 bits per FAT entry, thus two entries span 3 bytes.^ The total size of the File System in bytes.
  • Using Default Tools - Database Tables 15 January 2010 7:15 UTC www.hp.com [Source type: Reference]

^ Thus, a handle entry is 8-bytes on 32-bit Windows and 12-bytes on 64-bit Windows.
  • Mark's Blog 15 January 2010 7:15 UTC blogs.technet.com [Source type: FILTERED WITH BAYES]

^ FAT File System Disk Volume Structures Describes the disk volume structures used in the FAT file system.
  • file allocation table definition - Wi-FiPlanet.com 15 January 2010 7:15 UTC wi-fiplanet.webopedia.com [Source type: General]

.It is consistently little-endian: if you consider the 3 bytes as one little-endian 24-bit number, the 12 least significant bits are the first entry and the 12 most significant bits are the second.^ On any reasonably busy system you will likely get a number quite a bit larger than 4GB. .
  • Mark's Blog : Pushing the Limits of Windows: Virtual Memory 15 January 2010 7:15 UTC blogs.technet.com [Source type: FILTERED WITH BAYES]

^ The maximum size of an extent is 2 24 -1 blocks, or almost 64GiB. There are a few types of extents, one of them is ABNR which describes an extent contaning zero bytes only.

^ You may recall that if you need to DELETE a large number of rows from a table, an efficient option is to truncate or even drop the table rather than deleting one row at a time.
  • SQL Server Storage Engine 15 January 2010 7:15 UTC blogs.msdn.com [Source type: FILTERED WITH BAYES]

.In the FAT32 file system, FAT entries are 32 bits, but only 28 of these are actually used; the 4 most significant bits are reserved.^ Everything within NTFS, including metadata, is stored as a file accessible in the file system namespace and described by entries in the MFT. .
  • Scalability and Performance in Modern Filesystems 15 January 2010 7:15 UTC oss.sgi.com [Source type: Reference]

^ This paper compares the XFS file system with three other file systems in widespread use today: .
  • Scalability and Performance in Modern Filesystems 15 January 2010 7:15 UTC oss.sgi.com [Source type: Reference]

^ By using the vfs/vnode interface, the file system works with the standard Solaris OS kernel and requires no modifications to the kernel for file management support.
  • C H A P T E R 1 - File System Overview 15 January 2010 7:15 UTC docs.sun.com [Source type: Reference]

FAT entry values:
FAT12 FAT16 FAT32 Description
0x000 0x0000 0x00000000 Free Cluster
0x001 0x0001 0x00000001 Reserved value; do not use
0x002–0xFEF 0x0002–0xFFEF 0x00000002–0x0FFFFFEF Used cluster; value points to next cluster
0xFF0–0xFF6 0xFFF0–0xFFF6 0x0FFFFFF0–0x0FFFFFF6 Reserved values; do not use[28].
0xFF7 0xFFF7 0x0FFFFFF7 Bad sector in cluster or reserved cluster
0xFF8–0xFFF 0xFFF8–0xFFFF 0x0FFFFFF8–0x0FFFFFFF Last cluster in file
.Note that FAT32 uses only 28 bits of the 32 possible bits.^ In other words, they use no more than 32 bits to store the length of the file.
  • Scalability and Performance in Modern Filesystems 15 January 2010 7:15 UTC oss.sgi.com [Source type: Reference]

^ Concurrent mode (classical and enhanced) The classical concurrent mode volume groups (VGs) only supported Serial DASD and SSA disks in conjunction with the 32-bit kernel.

^ A process on 32-bit Windows will use slightly less resident memory because its kernel-mode thread stack is smaller.
  • Mark's Blog 15 January 2010 7:15 UTC blogs.technet.com [Source type: FILTERED WITH BAYES]

The upper 4 bits are usually zero (as indicated in the table above) but are reserved and should be left untouched.
.The first cluster of the Data Region is cluster #2. That leaves the first two entries of the FAT unused.^ In block 2905, the system sets the variables Offset and Len and writes the data to a data region starting at the first location in free space.
  • Method and system for file system management using a flash-erasable, programmable, read-only memory - Patent 6256642 15 January 2010 7:15 UTC www.freepatentsonline.com [Source type: Reference]

^ In block 3007, the system copies the region data corresponding to the Alloc[j] entry to the spare block.
  • Method and system for file system management using a flash-erasable, programmable, read-only memory - Patent 6256642 15 January 2010 7:15 UTC www.freepatentsonline.com [Source type: Reference]

^ The FEProm manager allocates another entry for the data region.
  • Method and system for file system management using a flash-erasable, programmable, read-only memory - Patent 6256642 15 January 2010 7:15 UTC www.freepatentsonline.com [Source type: Reference]

.In the first byte of the first entry a copy of the media descriptor is stored.^ The file systems do not, for example, store data from one file in the first 50 bytes of a block and data from another file the last 78 bytes of a 128-byte block.
  • Method and system for file system management using a flash-erasable, programmable, read-only memory - Patent 6256642 15 January 2010 7:15 UTC www.freepatentsonline.com [Source type: Reference]

^ That means a page, which is 4096 bytes on both x86 and x64, can store 512 entries on 32-bit Windows and 256 entries on 64-bit Windows.
  • Mark's Blog 15 January 2010 7:15 UTC blogs.technet.com [Source type: FILTERED WITH BAYES]

.The remaining 8 bits (if FAT16), or 20 bits (if FAT32) of this entry are 1. In the second entry the end-of-cluster-chain marker is stored.^ That means a page, which is 4096 bytes on both x86 and x64, can store 512 entries on 32-bit Windows and 256 entries on 64-bit Windows.
  • Mark's Blog 15 January 2010 7:15 UTC blogs.technet.com [Source type: FILTERED WITH BAYES]

.The high order two bits of the second entry are sometimes, in the case of FAT16 and FAT32, used for dirty volume management: high order bit 1: last shutdown was clean; next highest bit 1: during the previous mount no disk I/O errors were detected.^ Volume Manager Software that creates and manages disk volumes.
  • Scalability and Performance in Modern Filesystems 15 January 2010 7:15 UTC oss.sgi.com [Source type: Reference]

^ File System The software used to organize and manage the data stored on disk drives.
  • Scalability and Performance in Modern Filesystems 15 January 2010 7:15 UTC oss.sgi.com [Source type: Reference]

^ It appeared that the Lisa_client process performed a SCSI pass-through command to the disk hosting the C: volume that timed-out after three minutes with a hardware error.
  • Mark's Blog 15 January 2010 7:15 UTC blogs.technet.com [Source type: FILTERED WITH BAYES]

[31]

Directory table

.A directory table is a special type of file that represents a directory (also known as a folder).^ FIG. 1B represents just one possible linked list arrangement that represents FIG. 1A. The arrangement would be different if files had been added but then deleted or if the name of a directory was changed.
  • Method and system for file system management using a flash-erasable, programmable, read-only memory - Patent 6256642 15 January 2010 7:15 UTC www.freepatentsonline.com [Source type: Reference]

^ This view links the nodeSubTypesEnum table enumOrd field with an (English) string representing the system sub type.
  • Using Default Tools - Database Tables 15 January 2010 7:15 UTC www.hp.com [Source type: Reference]

^ Since the aggregate inode table file refers to itself, the first extent of its inode allocation map has a well known constant address (just after the superblock).

.Each file or directory stored within it is represented by a 32-byte entry in the table.^ A directory within a directory in a hierarchical file system.
  • http://www.redhat.com/docs/glossary/index.html 15 January 2010 7:15 UTC www.redhat.com [Source type: Reference]

^ The name of a directory or file is changed by allocating a new DirEntry or FileEntry, respectively, and then setting the SecondaryPtr of the old entry to point the new entry.
  • Method and system for file system management using a flash-erasable, programmable, read-only memory - Patent 6256642 15 January 2010 7:15 UTC www.freepatentsonline.com [Source type: Reference]

^ Everything within NTFS, including metadata, is stored as a file accessible in the file system namespace and described by entries in the MFT. .
  • Scalability and Performance in Modern Filesystems 15 January 2010 7:15 UTC oss.sgi.com [Source type: Reference]

.Each entry records the name, extension, attributes (archive, directory, hidden, read-only, system and volume), the date and time of creation, the address of the first cluster of the file/directory's data and finally the size of the file/directory.^ A directory within a directory in a hierarchical file system.
  • http://www.redhat.com/docs/glossary/index.html 15 January 2010 7:15 UTC www.redhat.com [Source type: Reference]

^ A file will have an entry for each name change.
  • Method and system for file system management using a flash-erasable, programmable, read-only memory - Patent 6256642 15 January 2010 7:15 UTC www.freepatentsonline.com [Source type: Reference]

^ It is determined at file system creation time and depends on fragment size (which is user selectable).

.Aside from the Root Directory Table in FAT12 and FAT16 file systems, which occupies the special Root Directory Region location, all Directory Tables are stored in the Data Region.^ A directory within a directory in a hierarchical file system.
  • http://www.redhat.com/docs/glossary/index.html 15 January 2010 7:15 UTC www.redhat.com [Source type: Reference]

^ A piece of data stored as a single addressable object on a file system.
  • http://www.redhat.com/docs/glossary/index.html 15 January 2010 7:15 UTC www.redhat.com [Source type: Reference]

^ The location of a file on a file system ; describes where the file resides in a directory structure.
  • http://www.redhat.com/docs/glossary/index.html 15 January 2010 7:15 UTC www.redhat.com [Source type: Reference]

The actual number of entries in a directory stored in the Data Region can grow by adding another cluster to the chain in the FAT.
.Note that before each entry there can be "fake entries" to support the Long File Name.^ A file will have an entry for each name change.
  • Method and system for file system management using a flash-erasable, programmable, read-only memory - Patent 6256642 15 January 2010 7:15 UTC www.freepatentsonline.com [Source type: Reference]

^ The name of a directory or file is changed by allocating a new DirEntry or FileEntry, respectively, and then setting the SecondaryPtr of the old entry to point the new entry.
  • Method and system for file system management using a flash-erasable, programmable, read-only memory - Patent 6256642 15 January 2010 7:15 UTC www.freepatentsonline.com [Source type: Reference]

^ The support for 64-bit files means that there are potentially a very large number of blocks to be indexed for every file.
  • Scalability and Performance in Modern Filesystems 15 January 2010 7:15 UTC oss.sgi.com [Source type: Reference]

(See further down the article).
Legal characters for DOS file names include the following:
.
  • Upper case letters AZ
  • Numbers 09
  • Space (though trailing spaces in either the base name or the extension are considered to be padding and not a part of the file name, also filenames with space in them could not be used on the DOS command line prior to Windows 95 because of the lack of a suitable escaping system)
  • !^ VFAT ) The file system used in older Windows operating systems, such as Windows 95.
    • http://www.redhat.com/docs/glossary/index.html 15 January 2010 7:15 UTC www.redhat.com [Source type: Reference]

    ^ In either case, you’ll need to use a debugger and the !htrace debugger command to view the trace information.
    • Mark's Blog 15 January 2010 7:15 UTC blogs.technet.com [Source type: FILTERED WITH BAYES]

    ^ Most file systems use linear bitmap structures to map free versus allocated space.
    • Scalability and Performance in Modern Filesystems 15 January 2010 7:15 UTC oss.sgi.com [Source type: Reference]

    # $ % & ' ( ) - @ ^ _ ` { } ~
  • Values 128–255
This excludes the following ASCII characters:
  • " * / : < > ? \ |
    .Windows/MSDOS has no shell escape character
  • + , . ; = [ ]
    They are allowed in long file names only.
  • Lower case letters az
    Stored as AZ.^ Submitted by C. Whitman on March 6, 2009 - 2:52 P.M. Microsoft's long filename patents have no bearing on Samba, since they are only relevant to the FAT file system and Samba does not use FAT. Fat is not a network file system.
    • Linux companies sign Microsoft patent protection pacts - Computerworld Blogs 15 January 2010 7:15 UTC blogs.computerworld.com [Source type: General]

    ^ In other words, they use no more than 32 bits to store the length of the file.
    • Scalability and Performance in Modern Filesystems 15 January 2010 7:15 UTC oss.sgi.com [Source type: Reference]

    ^ However, the use of a distinct FEProm manager allows an FEProm to store data from different file systems and even non-file system data.
    • Method and system for file system management using a flash-erasable, programmable, read-only memory - Patent 6256642 15 January 2010 7:15 UTC www.freepatentsonline.com [Source type: Reference]

    Allowed in long file names.
  • Control characters 0–31
  • Value 127 (DEL)
.The DOS file names are in the OEM character set.^ The name of a directory or file is changed by allocating a new DirEntry or FileEntry, respectively, and then setting the SecondaryPtr of the old entry to point the new entry.
  • Method and system for file system management using a flash-erasable, programmable, read-only memory - Patent 6256642 15 January 2010 7:15 UTC www.freepatentsonline.com [Source type: Reference]

^ In block 1905, the system sets C-> Name equal to the new file name and sets C-> Attributes, C-> Date, C-> Time, and sets C-> Status based on the file entry being superseded to ATDRecent.
  • Method and system for file system management using a flash-erasable, programmable, read-only memory - Patent 6256642 15 January 2010 7:15 UTC www.freepatentsonline.com [Source type: Reference]

^ In block 1901, the system searches through the directory structure and locates the file whose name is to be changed and sets the variable P to point to the FileEntry.
  • Method and system for file system management using a flash-erasable, programmable, read-only memory - Patent 6256642 15 January 2010 7:15 UTC www.freepatentsonline.com [Source type: Reference]

Directory entries, both in the Root Directory Region and in subdirectories, are of the following format (see also 8.3 filename):
Byte Offset Length Description
0x00 8 DOS file name (padded with spaces)
The first byte can have the following special values:
0x00 Entry is available and no subsequent entry is in use
0x05 Initial character is actually 0xE5.
0x2E 'Dot' entry; either '.' or '..'
0xE5 Entry has been previously erased and is available. File undelete utilities must replace this character with a regular character as part of the undeletion process.
0x08 3 DOS file extension (padded with spaces)
0x0b 1 File Attributes
Bit Mask Description
0 0x01 Read Only
1 0x02 Hidden
2 0x04 System
3 0x08 Volume Label
4 0x10 Subdirectory
5 0x20 Archive
6 0x40 Device (internal use only, never found on disk)
7 0x80 Unused
.An attribute value of 0x0F is used to designate a long file name entry.^ A file will have an entry for each name change.
  • Method and system for file system management using a flash-erasable, programmable, read-only memory - Patent 6256642 15 January 2010 7:15 UTC www.freepatentsonline.com [Source type: Reference]

^ The name of a directory or file is changed by allocating a new DirEntry or FileEntry, respectively, and then setting the SecondaryPtr of the old entry to point the new entry.
  • Method and system for file system management using a flash-erasable, programmable, read-only memory - Patent 6256642 15 January 2010 7:15 UTC www.freepatentsonline.com [Source type: Reference]

^ In block 1905, the system sets C-> Name equal to the new file name and sets C-> Attributes, C-> Date, C-> Time, and sets C-> Status based on the file entry being superseded to ATDRecent.
  • Method and system for file system management using a flash-erasable, programmable, read-only memory - Patent 6256642 15 January 2010 7:15 UTC www.freepatentsonline.com [Source type: Reference]

0x0c 1 Reserved; two bits are used by NT and later versions to encode case information (see below); otherwise 0[32]
0x0d 1 Create time, fine resolution: 10ms units, values from 0 to 199.
0x0e 2 Create time. The hour, minute and second are encoded according to the following bitmap:
Bits Description
15-11 Hours (0-23)
10-5 Minutes (0-59)
4-0 Seconds/2 (0-29)
Note that the seconds is recorded only to a 2 second resolution. Finer resolution for file creation is found at offset 0x0d.
0x10 2 Create date. The year, month and day are encoded according to the following bitmap:
Bits Description
15-9 Year (0 = 1980, 127 = 2107)
8-5 Month (1 = January, 12 = December)
4-0 Day (1 - 31)
0x12 2 Last access date; see offset 0x10 for description.
0x14 2 EA-Index (used by OS/2 and NT) in FAT12 and FAT16, High 2 bytes of first cluster number in FAT32
0x16 2 Last modified time; see offset 0x0e for description.
0x18 2 Last modified date; see offset 0x10 for description.
0x1a 2 First cluster in FAT12 and FAT16. Low 2 bytes of first cluster in FAT32. Entries with the Volume Label flag, subdirectory ".." pointing to root, and empty files with size 0 should have first cluster 0.
0x1c 4 File size in bytes. Entries with the Volume Label or Subdirectory flag set should have a size of 0.
.Clusters are numbered from a cluster offset as defined above and the FilestartCluster is in 0x1a.^ Cluster (NT) In NT parlance, the term cluster is defined as a number of physical disk blocks allocated as a unit.
  • Scalability and Performance in Modern Filesystems 15 January 2010 7:15 UTC oss.sgi.com [Source type: Reference]

This would mean the first data segment X can be calculated using the Boot Sector fields:
For FAT32
FileStartSector = ReservedSectors(0x0e) + (NumofFAT(0x10) * Sectors2FAT(0x24)) + ((X − 2) * SectorsPerCluster(0x0d))
For FAT16/12
FileStartSector = ReservedSectors(0x0e) + (NumofFAT(0x10) * Sectors2FAT(0x16)) + (MaxRootEntry(0x11) * 32 / BytesPerSector(0x0b)) + ((X − 2) * SectorsPerCluster(0x0d))

Long file names

.Long File Names (LFN) are stored on a FAT file system using a trick—adding (possibly multiple) additional entries into the directory before the normal file entry.^ A file will have an entry for each name change.
  • Method and system for file system management using a flash-erasable, programmable, read-only memory - Patent 6256642 15 January 2010 7:15 UTC www.freepatentsonline.com [Source type: Reference]

^ This file system uses a hierarchical approach to storing files.
  • Method and system for file system management using a flash-erasable, programmable, read-only memory - Patent 6256642 15 January 2010 7:15 UTC www.freepatentsonline.com [Source type: Reference]

^ Should I use 1 file or multiple files for TempDB? .
  • SQL Server Storage Engine 15 January 2010 7:15 UTC blogs.msdn.com [Source type: FILTERED WITH BAYES]

.The additional entries are marked with the Volume Label, System, Hidden, and Read Only attributes (yielding 0x0F), which is a combination that is not expected in the MS-DOS environment, and therefore ignored by MS-DOS programs and third-party utilities.^ Therefore, under load when the log fills up and needs to be flushed, blocks actually have to be re-read from the log and then written to the file system.
  • Scalability and Performance in Modern Filesystems 15 January 2010 7:15 UTC oss.sgi.com [Source type: Reference]

^ Traditional Unix systems have used only a single read ahead buffer at a time.
  • Scalability and Performance in Modern Filesystems 15 January 2010 7:15 UTC oss.sgi.com [Source type: Reference]

^ The MS-DOS operating system, which is available from Microsoft Corporation of Redmond, Washington, implements a file system with a hierarchical directory structure.
  • Method and system for file system management using a flash-erasable, programmable, read-only memory - Patent 6256642 15 January 2010 7:15 UTC www.freepatentsonline.com [Source type: Reference]

Notably, a directory containing only volume labels is considered as empty and is allowed to be deleted; such a situation appears if files created with long names are deleted from plain DOS.
.Older versions of PC-DOS mistake LFN names in the root directory for the volume label, and are likely to display an incorrect label.^ Region 2410 contains the DirEntry for directory ROOT. The PrimaryPtr 2413 of directory ROOT points to Alloc[0] entry 2421 corresponding to directory DOS. Alloc[0] entry 2421 contains the variable Offset 2422, which contains the offset of region 2420.
  • Method and system for file system management using a flash-erasable, programmable, read-only memory - Patent 6256642 15 January 2010 7:15 UTC www.freepatentsonline.com [Source type: Reference]

^ For example, the path name ".backslash.P.backslash.C" means that a directory C is to be created that is a subdirectory of P, which is a subdirectory of the root directory.
  • Method and system for file system management using a flash-erasable, programmable, read-only memory - Patent 6256642 15 January 2010 7:15 UTC www.freepatentsonline.com [Source type: Reference]

^ The blocks labeled DOS, WORD, DAVID, and MARY represent directories, and the blocks labeled AUTOEXEC.BAT, COMMAND.COM, FORMAT.EXE, LETTER2.DOC, LETTER.DOC, and two files named LETTER1.DOC represent files.
  • Method and system for file system management using a flash-erasable, programmable, read-only memory - Patent 6256642 15 January 2010 7:15 UTC www.freepatentsonline.com [Source type: Reference]

.Each phony entry can contain up to 13 UTF-16 characters (26 bytes) by using fields in the record which contain file size or time stamps (but not the starting cluster field, for compatibility with disk utilities, the starting cluster field is set to a value of 0. See 8.3 filename for additional explanations).^ The total size of the File System in bytes.
  • Using Default Tools - Database Tables 15 January 2010 7:15 UTC www.hp.com [Source type: Reference]

^ File metadata includes date and time stamps, ownership, access permissions, other security information such as access control lists (ACLs) if they exist, the files size and the storage location or locations on disk.
  • Scalability and Performance in Modern Filesystems 15 January 2010 7:15 UTC oss.sgi.com [Source type: Reference]

^ To optimally size your paging file you should start all the applications you run at the same time, load typical data sets, and then note the commit charge peak (or look at this value after a period of time where you know maximum load was attained).
  • Mark's Blog 15 January 2010 7:15 UTC blogs.technet.com [Source type: FILTERED WITH BAYES]

.Up to 20 of these 13-character entries may be chained, supporting a maximum length of 255 UTF-16 characters.^ As more entries are loaded, the areas of free memory are broken up and the shared pool may become fragmented.

^ Pool nonpaged bytes Pool paged bytes (virtual size of paged pool – some may be paged out) Pool paged resident bytes (physical size of paged pool) However, there are no performance counters for the maximum size of these pools.
  • Mark's Blog 15 January 2010 7:15 UTC blogs.technet.com [Source type: FILTERED WITH BAYES]

[32]
After the last UTF-16 character, a 0x00 0x00 is added. Other not used characters are filled with 0xFF 0xFF.
LFN entries use the following format:
Byte Offset Length Description
0x00 1 Sequence Number
0x01 10 Name characters (five UTF-16 characters)
0x0b 1 Attributes (always 0x0F)
0x0c 1 Reserved (always 0x00)
0x0d 1 Checksum of DOS file name
0x0e 12 Name characters (six UTF-16 characters)
0x1a 2 First cluster (always 0x0000)
0x1c 4 Name characters (two UTF-16 characters)
.If there are multiple LFN entries, required to represent a file name, firstly comes the last LFN entry (the last part of the filename).^ A file will have an entry for each name change.
  • Method and system for file system management using a flash-erasable, programmable, read-only memory - Patent 6256642 15 January 2010 7:15 UTC www.freepatentsonline.com [Source type: Reference]

^ The name of a directory or file is changed by allocating a new DirEntry or FileEntry, respectively, and then setting the SecondaryPtr of the old entry to point the new entry.
  • Method and system for file system management using a flash-erasable, programmable, read-only memory - Patent 6256642 15 January 2010 7:15 UTC www.freepatentsonline.com [Source type: Reference]

^ FIG. 1B represents just one possible linked list arrangement that represents FIG. 1A. The arrangement would be different if files had been added but then deleted or if the name of a directory was changed.
  • Method and system for file system management using a flash-erasable, programmable, read-only memory - Patent 6256642 15 January 2010 7:15 UTC www.freepatentsonline.com [Source type: Reference]

.The sequence number here also has bit 7 (0x40) checked (this means the last LFN entry.^ The handle contains two parts: (1) a logical block sequence number, which indirectly references a physical block, and (2) an index to an Alloc entry, which indirectly references a region within the physical block.
  • Method and system for file system management using a flash-erasable, programmable, read-only memory - Patent 6256642 15 January 2010 7:15 UTC www.freepatentsonline.com [Source type: Reference]

^ Here’s the definition for a handle entry on 64-bit Windows, as shown in a kernel debugger using the dt (dump type) command: .
  • Mark's Blog 15 January 2010 7:15 UTC blogs.technet.com [Source type: FILTERED WITH BAYES]

^ That means a page, which is 4096 bytes on both x86 and x64, can store 512 entries on 32-bit Windows and 256 entries on 64-bit Windows.
  • Mark's Blog 15 January 2010 7:15 UTC blogs.technet.com [Source type: FILTERED WITH BAYES]

.However it's the first entry got when reading the directory file).^ The name of a directory or file is changed by allocating a new DirEntry or FileEntry, respectively, and then setting the SecondaryPtr of the old entry to point the new entry.
  • Method and system for file system management using a flash-erasable, programmable, read-only memory - Patent 6256642 15 January 2010 7:15 UTC www.freepatentsonline.com [Source type: Reference]

^ A directory or file record is deleted from the linked list by setting the status of the directory or file entry.
  • Method and system for file system management using a flash-erasable, programmable, read-only memory - Patent 6256642 15 January 2010 7:15 UTC www.freepatentsonline.com [Source type: Reference]

^ The first hit was a directory enumeration operation with the file names showing as results in the Details column on the far right: .
  • Mark's Blog 15 January 2010 7:15 UTC blogs.technet.com [Source type: FILTERED WITH BAYES]

.The last LFN entry has the biggest sequence number which decreases in following entries.^ The handle contains two parts: (1) a logical block sequence number, which indirectly references a physical block, and (2) an index to an Alloc entry, which indirectly references a region within the physical block.
  • Method and system for file system management using a flash-erasable, programmable, read-only memory - Patent 6256642 15 January 2010 7:15 UTC www.freepatentsonline.com [Source type: Reference]

.The first LFN entry has sequence number 1. Bit 8 (0x80) of the sequence number is used to indicate that the entry is deleted.^ Here’s the definition for a handle entry on 64-bit Windows, as shown in a kernel debugger using the dt (dump type) command: .
  • Mark's Blog 15 January 2010 7:15 UTC blogs.technet.com [Source type: FILTERED WITH BAYES]

^ The FEProm manager uses a logical block sequence number, variable BlockSeq in the header, to identify a specific logical block of data.
  • Method and system for file system management using a flash-erasable, programmable, read-only memory - Patent 6256642 15 January 2010 7:15 UTC www.freepatentsonline.com [Source type: Reference]

^ The handle contains two parts: (1) a logical block sequence number, which indirectly references a physical block, and (2) an index to an Alloc entry, which indirectly references a region within the physical block.
  • Method and system for file system management using a flash-erasable, programmable, read-only memory - Patent 6256642 15 January 2010 7:15 UTC www.freepatentsonline.com [Source type: Reference]

For example if we have filename "File with very long filename.ext" it would be formatted like this:
Sequence number Entry data
0x43 "me.ext"
0x02 "y long filena"
0x01 "File with ver"
??? Normal 8.3 entry
.A checksum also allows verification of whether a long file name matches the 8.3 name; such a mismatch could occur if a file was deleted and re-created using DOS in the same directory position.^ The file system allows for directories to be added and deleted, and files to be created, extended, and modified.
  • Method and system for file system management using a flash-erasable, programmable, read-only memory - Patent 6256642 15 January 2010 7:15 UTC www.freepatentsonline.com [Source type: Reference]

^ The name of a directory or file is changed by allocating a new DirEntry or FileEntry, respectively, and then setting the SecondaryPtr of the old entry to point the new entry.
  • Method and system for file system management using a flash-erasable, programmable, read-only memory - Patent 6256642 15 January 2010 7:15 UTC www.freepatentsonline.com [Source type: Reference]

^ FIG. 1B represents just one possible linked list arrangement that represents FIG. 1A. The arrangement would be different if files had been added but then deleted or if the name of a directory was changed.
  • Method and system for file system management using a flash-erasable, programmable, read-only memory - Patent 6256642 15 January 2010 7:15 UTC www.freepatentsonline.com [Source type: Reference]

The checksum is calculated using the algorithm below. (Note that pFcbName is a pointer to the name as it appears in a regular directory entry, i.e. the first eight characters are the filename, and the last three are the extension. The dot is implicit. Any unused space in the filename is padded with spaces (ASCII 0x20) char. For example, "Readme.txt" would be "README  TXT".)
unsigned char lfn_checksum(const unsigned char *pFcbName)
{
    int i;
    unsigned char sum=0;
 
    for (i=11; i; i--)
        sum = ((sum & 1) << 7) + (sum >> 1) + *pFcbName++;
    return sum;
}
.If a filename contains only lowercase letters, or is a combination of a lowercase basename with an uppercase extension, or vice-versa; and has no special characters, and fits within the 8.3 limits, a VFAT entry is not created on Windows NT and later versions such as XP. Instead, two bits in byte 0x0c of the directory entry are used to indicate that the filename should be considered as entirely or partially lowercase.^ GB 32-bit Windows XP .
  • Mark's Blog 15 January 2010 7:15 UTC blogs.technet.com [Source type: FILTERED WITH BAYES]

^ GB 64-bit Windows XP .
  • Mark's Blog 15 January 2010 7:15 UTC blogs.technet.com [Source type: FILTERED WITH BAYES]

^ There is a special when an insert causes a row version to be created but I will cover that later to keep this topic simple.
  • SQL Server Storage Engine 15 January 2010 7:15 UTC blogs.msdn.com [Source type: FILTERED WITH BAYES]

.Specifically, bit 4 means lowercase extension and bit 3 lowercase basename, which allows for combinations such as "example.TXT" or "HELLO.txt" but not "Mixed.txt". Few other operating systems support this.^ Note that the page size is operating-system specific and generally cannot be changed.

^ If it is writing to the file it may allow other processes to read from the file, for example, but not to also write to the file.
  • Mark's Blog 15 January 2010 7:15 UTC blogs.technet.com [Source type: FILTERED WITH BAYES]

^ For example, there are virtual memory limits that apply to individual processes that run applications, the operating system, and for the system as a whole.
  • Mark's Blog : Pushing the Limits of Windows: Virtual Memory 15 January 2010 7:15 UTC blogs.technet.com [Source type: FILTERED WITH BAYES]
  • Mark's Blog 15 January 2010 7:15 UTC blogs.technet.com [Source type: FILTERED WITH BAYES]

.This creates a backwards-compatibility problem with older Windows versions (95, 98, ME) that see all-uppercase filenames if this extension has been used, and therefore can change the name of a file when it is transported, such as on a USB flash drive.^ A file will have an entry for each name change.
  • Method and system for file system management using a flash-erasable, programmable, read-only memory - Patent 6256642 15 January 2010 7:15 UTC www.freepatentsonline.com [Source type: Reference]

^ The name of a directory or file is changed by allocating a new DirEntry or FileEntry, respectively, and then setting the SecondaryPtr of the old entry to point the new entry.
  • Method and system for file system management using a flash-erasable, programmable, read-only memory - Patent 6256642 15 January 2010 7:15 UTC www.freepatentsonline.com [Source type: Reference]

^ FIG. 1B represents just one possible linked list arrangement that represents FIG. 1A. The arrangement would be different if files had been added but then deleted or if the name of a directory was changed.
  • Method and system for file system management using a flash-erasable, programmable, read-only memory - Patent 6256642 15 January 2010 7:15 UTC www.freepatentsonline.com [Source type: Reference]

.Current 2.6.x versions of Linux will recognize this extension when reading (source: kernel 2.6.18 /fs/fat/dir.c and fs/vfat/namei.c); the mount option shortname determines whether this feature is used when writing.^ Pavel: "enable better use of *virtual* memory, given that physical memory is allocated on demand" and then "reading from/writing to the committed pages [...
  • Mark's Blog : Pushing the Limits of Windows: Virtual Memory 15 January 2010 7:15 UTC blogs.technet.com [Source type: FILTERED WITH BAYES]

^ If the number of writes exceeds a threshold number, then the manager determines whether any blocks should be reclaimed.
  • Method and system for file system management using a flash-erasable, programmable, read-only memory - Patent 6256642 15 January 2010 7:15 UTC www.freepatentsonline.com [Source type: Reference]

^ An application that wants to be really fancy could determine whether the data will fit and use cached or non-cached I/O accordingly.
  • Mark's Blog : Pushing the Limits of Windows: Virtual Memory 15 January 2010 7:15 UTC blogs.technet.com [Source type: FILTERED WITH BAYES]

[33]

Third-party extensions

.Before Microsoft added support for long filenames and creation/access time stamps, bytes 0x0C–0x15 of the directory entry were used by alternative operating systems to store additional metadata.^ Virtual memory separates a program’s view of memory from the system’s physical memory, so an operating system decides when and if to store the program’s code and data in physical memory and when to store it in a file.
  • Mark's Blog : Pushing the Limits of Windows: Virtual Memory 15 January 2010 7:15 UTC blogs.technet.com [Source type: FILTERED WITH BAYES]
  • Mark's Blog 15 January 2010 7:15 UTC blogs.technet.com [Source type: FILTERED WITH BAYES]

^ Microsoft created a version of Winlogon and the kernel with additional diagnostic information and tried to reproduce the problem on lab systems configured identically to the client’s, but without success.
  • Mark's Blog 15 January 2010 7:15 UTC blogs.technet.com [Source type: FILTERED WITH BAYES]

^ Operating system page table entries are then pre-built for each page of the SGA. This setting may increase the amount of time necessary for instance startup, but it is likely to decrease the amount of time necessary for Oracle to reach its full performance capacity after startup.

These included:
Byte Offset Length System Description
0x0C 2 RISC OS File type, 0x000 - 0xFFF
0x0C 1 DOS Plus User-defined file attributes F1-F4
Bit Mask Description
7 0x80 F1
6 0x40 F2
5 0x20 F3
4 0x10 F4
0x0C 1 MSX-DOS 2 For a deleted file, the original first character of the filename.
0x0D 1 DR-DOS For a deleted file, the original first character of the filename.
0x0E 2 DR-DOS and FlexOS Encrypted file password
0x0E 2 ANDOS File address in the memory
0x10 4 DR-DOS 7 For a deleted file, its original file time and date; deleted files have their normal time and date fields set to the time of deletion
0x12 2 DR-DOS 6 and FlexOS File owner ID
0x14 2 DR-DOS and FlexOS File permissions bitmap (execute permissions are only used by FlexOS):
Bit Mask Description
0 0x0001 Owner delete requires password
1 0x0002 Owner execute requires password
2 0x0004 Owner write requires password
3 0x0008 Owner read requires password
4 0x0010 Group delete requires password
5 0x0020 Group execute requires password
6 0x0040 Group write requires password
7 0x0080 Group read requires password
8 0x0100 World delete requires password
9 0x0200 World execute requires password
10 0x0400 World write requires password
11 0x0800 World read requires password

FAT licensing

Microsoft applied for, and was granted, a series of patents for key parts of the FAT file system in the mid-1990s. Being almost universally compatible and well-understood, FAT is frequently chosen as an interchange format for flash media used in digital cameras and PDAs.
.On December 3, 2003 Microsoft announced[34] it would be offering licenses for use of its FAT specification and "associated intellectual property", at the cost of a US$0.25 royalty per unit sold, with a $250,000 maximum royalty per license agreement.^ Windows XP and Windows Server 2003 set the maximum nonpaged pool to a little over 400K per MB of RAM or 128GB, whichever is smaller.
  • Mark's Blog 15 January 2010 7:15 UTC blogs.technet.com [Source type: FILTERED WITH BAYES]

[35]
To this end, Microsoft cited four patents on the FAT file system as the basis of its intellectual property claims. All four pertain to long-filename extensions to FAT first seen in Windows 95:
.
  • U.S. Patent 5,745,902 - Method and system for accessing a file using file names having different file name formats.^ When you partition your buffer cache into multiple buffer pools, each buffer pool can be used for blocks from objects that are accessed in different ways.

    ^ When you access a file on the share, the file server driver on that system uses the token from the logon session for the permission check, leveraging a mechanism called impersonation .
    • Mark's Blog 15 January 2010 7:15 UTC blogs.technet.com [Source type: FILTERED WITH BAYES]

    ^ So that multiple executables with the same name but in different directories get their own prefetch file, the Logical Prefetcher gives the file a name that’s a concatenation of the executable image name and the hash of the path in which the image is stored e.g.
    • Mark's Blog 15 January 2010 7:15 UTC blogs.technet.com [Source type: FILTERED WITH BAYES]

    .Filed July 6, 1992. This covered a means of generating and associating a short, 8.3 filename with long one (for example, "Microsoft.txt" with "MICROS~1.TXT") and a means of enumerating conflicting short filenames (for example, "MICROS~2.TXT" and "MICROS~3.TXT").^ One example is bar code data associated with an Element that also has an asset tag.
    • Using Default Tools - Database Tables 15 January 2010 7:15 UTC www.hp.com [Source type: Reference]

    It is unclear whether this patent would cover an implementation of FAT without explicit long filename capabilities. Hard links in Unix file systems do not appear to be prior art: deleting a FAT file via its long name will also remove its short name. .Renaming a file to a "short" name also updates the long file name for coherency; similarly, renaming a file to a "long" name will allocate a new "short" name.^ Names are simply user-friendly representations for SIDs, allowing you to rename an account and not have to update access control lists (ACLs) that reference the account to reflect the change.
    • Mark's Blog 15 January 2010 7:15 UTC blogs.technet.com [Source type: FILTERED WITH BAYES]

    In NTFS, hard links and dual names are separate concepts and each hard link has two names. .Finally, at the API level, both names are always provided together when a directory lookup is requested from the system; they do not appear as two separate files and do not have to be "matched" to determine unique files.
  • U.S. Patent 5,579,517 - Common name space for long and short filenames.^ Virtual memory separates a program’s view of memory from the system’s physical memory, so an operating system decides when and if to store the program’s code and data in physical memory and when to store it in a file.
    • Mark's Blog : Pushing the Limits of Windows: Virtual Memory 15 January 2010 7:15 UTC blogs.technet.com [Source type: FILTERED WITH BAYES]
    • Mark's Blog 15 January 2010 7:15 UTC blogs.technet.com [Source type: FILTERED WITH BAYES]

    ^ Two separate occurrences of a SQL statement or PL/SQL block can use a shared SQL area if they are identical according to these criteria: .

    ^ However, PMIE cannot modify other locations in a user’s account, like documents folders and per-user autostart locations in the registry and file system, because they have an integrity level of Medium.
    • Mark's Blog 15 January 2010 7:15 UTC blogs.technet.com [Source type: FILTERED WITH BAYES]

    .Filed for on 1995-04-24. This covers the method of chaining together multiple consecutive 8.3 named directory entries to hold long filenames, with some of the entries specially marked to prevent their confusing older, long filename-unaware FAT implementations.^ The first hit was a directory enumeration operation with the file names showing as results in the Details column on the far right: .
    • Mark's Blog 15 January 2010 7:15 UTC blogs.technet.com [Source type: FILTERED WITH BAYES]

    ^ So that multiple executables with the same name but in different directories get their own prefetch file, the Logical Prefetcher gives the file a name that’s a concatenation of the executable image name and the hash of the path in which the image is stored e.g.
    • Mark's Blog 15 January 2010 7:15 UTC blogs.technet.com [Source type: FILTERED WITH BAYES]

    ^ Some operating systems, however, have a special implementation for shared memory whereby you can change the page size.

  • U.S. Patent 5,758,352 - Common name space for long and short filenames. .Filed on 1996-09-05. This is very similar to 5,579,517.
    • The Public Patent Foundation successfully challenged this patent (USPTO); The USPTO rejected this patent on 2005-10-05, on the grounds that "the six assignees names were incorrect".[38][39] This decision was also later overturned by the Patent Office on 2006-01-10.
  • U.S. Patent 6,286,013 - Method and system for providing a common name space for long and short file names in an operating system.^ Virtual memory separates a program’s view of memory from the system’s physical memory, so an operating system decides when and if to store the program’s code and data in physical memory and when to store it in a file.
    • Mark's Blog : Pushing the Limits of Windows: Virtual Memory 15 January 2010 7:15 UTC blogs.technet.com [Source type: FILTERED WITH BAYES]
    • Mark's Blog 15 January 2010 7:15 UTC blogs.technet.com [Source type: FILTERED WITH BAYES]

    ^ The pool manager operates in kernel mode, using regions of the system’s virtual address space (described in the Pushing the Limits post on virtual memory) for the memory it sub-allocates.
    • Mark's Blog 15 January 2010 7:15 UTC blogs.technet.com [Source type: FILTERED WITH BAYES]

    ^ The first hit was a directory enumeration operation with the file names showing as results in the Details column on the far right: .
    • Mark's Blog 15 January 2010 7:15 UTC blogs.technet.com [Source type: FILTERED WITH BAYES]

    .Filed on 1997-01-28. This makes claims on the methods used when Windows 95, Windows 98 and Windows Me expose long filenames to their MS-DOS compatibility layer.^ I would like to know how I can tweak my paging files to make sure I am using the RAM optimally once I install the additional 16 Gb .
    • Mark's Blog : Pushing the Limits of Windows: Virtual Memory 15 January 2010 7:15 UTC blogs.technet.com [Source type: FILTERED WITH BAYES]

    ^ Monday, December 01, 2008 12:28 PM by Luke Skywalker # re: Pushing the Limits of Windows: Virtual Memory .
    • Mark's Blog : Pushing the Limits of Windows: Virtual Memory 15 January 2010 7:15 UTC blogs.technet.com [Source type: FILTERED WITH BAYES]

    It does not appear to affect any non-Microsoft FAT implementations.
.Many technical commentators have concluded that these patents only cover FAT implementations that include support for long filenames, and that removable solid state media and consumer devices only using short names would be unaffected.^ One example would be to hold the Operating System user friendly name for the device in this property.
  • Using Default Tools - Database Tables 15 January 2010 7:15 UTC www.hp.com [Source type: Reference]

^ At steady state, the number of buffers in the DEFAULT buffer pool being consumed by segments that would normally go in the RECYCLE buffer pool can be divided by four.

^ There would be no reason for Mark to talk about how these things are not useful to the discussion to make his point.
  • Mark's Blog : Pushing the Limits of Windows: Virtual Memory 15 January 2010 7:15 UTC blogs.technet.com [Source type: FILTERED WITH BAYES]

Additionally, in the document "Microsoft Extensible Firmware Initiative FAT 32 File System Specification, FAT: General Overview of On-Disk Format" published by Microsoft (version 1.03, 2000-12-06), Microsoft specifically grants a number of rights, which many readers have interpreted as permitting operating system vendors to implement FAT.
.Microsoft is not the only company to have applied for patents for parts of the FAT file system.^ So that the system’s virtual memory isn’t unnecessarily wasted, only part of the stack is initially allocated, or committed and the rest is simply reserved.
  • Mark's Blog 15 January 2010 7:15 UTC blogs.technet.com [Source type: FILTERED WITH BAYES]

^ As with all cases, Microsoft support began by asking about the system configuration, inventory of installed software, and about any recent changes the company had made to their systems.
  • Mark's Blog 15 January 2010 7:15 UTC blogs.technet.com [Source type: FILTERED WITH BAYES]

Other patents affecting FAT include:
.
  • U.S. Patent 5,367,671 - System for accessing extended object attribute (EA) data through file name or EA handle linkages in path tables.^ The name for this system obtained through DMI. .
    • Using Default Tools - Database Tables 15 January 2010 7:15 UTC www.hp.com [Source type: Reference]

    ^ The name for this system obtained through SNMP. .
    • Using Default Tools - Database Tables 15 January 2010 7:15 UTC www.hp.com [Source type: Reference]

    ^ Virtual memory separates a program’s view of memory from the system’s physical memory, so an operating system decides when and if to store the program’s code and data in physical memory and when to store it in a file.
    • Mark's Blog : Pushing the Limits of Windows: Virtual Memory 15 January 2010 7:15 UTC blogs.technet.com [Source type: FILTERED WITH BAYES]
    • Mark's Blog 15 January 2010 7:15 UTC blogs.technet.com [Source type: FILTERED WITH BAYES]

    Filed on 1990-09-25 by Barry A. Feigenbaum and Felix Miro of IBM, this makes claims on the methods used by OS/2, Windows NT, and Linux for storing extended attribute data in the "EA DATA. SF" file.

Appeal

As there was widespread call for these patents to be re-examined, the Public Patent Foundation (PUBPAT) submitted evidence to the US Patent and Trade Office (USPTO) disputing the validity of these patents, including prior art references from Xerox and IBM. The USPTO acknowledged that the evidence raised "substantial new question[s] of patentability," and opened an investigation into the validity of Microsoft's FAT patents.[40]
On 2004-09-30 the USPTO rejected all claims of U.S. Patent 5,579,517, based primarily on evidence provided by PUBPAT. Dan Ravicher, the foundation's executive director, said, "The Patent Office has simply confirmed what we already knew for some time now, Microsoft's FAT patent is bogus."
According to the PUBPAT press release, "Microsoft still has the opportunity to respond to the Patent Office's rejection. .Typically, third party requests for re-examination, like the one filed by PUBPAT, are successful in having the subject patent either narrowed or completely revoked roughly 70% of the time."^ Like getting an error in your program, just one is already too many, having your application write to a page file just once is very expensive, so just dont do it.
  • Mark's Blog : Pushing the Limits of Windows: Virtual Memory 15 January 2010 7:15 UTC blogs.technet.com [Source type: FILTERED WITH BAYES]

^ I think I'm leaning towards Ben on this one, with the caveat that having Pavel's "stormwater ponds" sounds like a good thing.
  • Mark's Blog : Pushing the Limits of Windows: Virtual Memory 15 January 2010 7:15 UTC blogs.technet.com [Source type: FILTERED WITH BAYES]

^ After you exit Testlimit, the commit limit will likely drop again when the memory manager truncates the tail of the paging file that it created to accommodate Testlimit's extreme commit requests.
  • Mark's Blog : Pushing the Limits of Windows: Virtual Memory 15 January 2010 7:15 UTC blogs.technet.com [Source type: FILTERED WITH BAYES]
  • Mark's Blog 15 January 2010 7:15 UTC blogs.technet.com [Source type: FILTERED WITH BAYES]

.On 2005-10-05 the Patent Office announced that, following the re-examination process, it had again rejected all claims of patent 5,579,517, and it additionally found U.S. Patent 5,758,352 invalid on the grounds that the patent had incorrect assignees.^ Saturday, January 10, 2009 6:05 PM by DarekS # re: JCAB .
  • Mark's Blog : Pushing the Limits of Windows: Virtual Memory 15 January 2010 7:15 UTC blogs.technet.com [Source type: FILTERED WITH BAYES]

Finally, on 2006-01-10 the Patent Office ruled that features of Microsoft's implementation of the FAT system were "novel and non-obvious", reversing both earlier non-final decisions.[41]

Patent infringement lawsuit

.In February 2009, Microsoft filed a patent infringement lawsuit against TomTom alleging that the device maker's products infringe on patents related to FAT32 filesystem.^ Comments Tuesday, February 03, 2009 6:00 AM The Case of the Phantom Desktop Files .
  • Mark's Blog 15 January 2010 7:15 UTC blogs.technet.com [Source type: FILTERED WITH BAYES]

.As some TomTom products are based on Linux, this marked the first time that Microsoft tried to enforce its patents against the Linux platform.^ A couple of weeks ago I participated for the first time in the keynote at Microsoft’s Teched US conference to a room of over 5,000 attendees.
  • Mark's Blog 15 January 2010 7:15 UTC blogs.technet.com [Source type: FILTERED WITH BAYES]

[42]. The lawsuit was settled out of court the following month with an agreement that Microsoft be given access to four of TomTom's patents, that TomTom will drop support for the FAT32 filesystem from its products, and that in return Microsoft not seek legal action against TomTom for the five year duration of the settlement agreement.[43]

Workarounds

.Developers of open source software have designed methods intended to circumvent Microsoft's patents.^ Alex came to our attention back when he was a primary contributor to the kernel of the ReactOS project, an attempt to develop an open source clone of Windows.
  • Mark's Blog 15 January 2010 7:15 UTC blogs.technet.com [Source type: FILTERED WITH BAYES]

[44]

See also

Notes and references

  1. ^ standards - Ecma-107
  2. ^ standards - ISO 9293:1987
  3. ^ standards - ISO/IEC 9293:1994
  4. ^ Microsoft Systems Journal Sept 1989 v4 n5 p1(13)
  5. ^ www.microsoft.com/mscorp/ip/tech/fathist.asp (archive.org)
  6. ^ a b c Duncan, Ray (1989). "Design goals and implementation of the new High Performance File System". Microsoft Systems Journal. http://cd.textfiles.com/megademo2/INFO/OS2_HPFS.TXT.  [Note: This particular text file has a number of 'scan' errors; e.g., "Ray" is the author's correct name; not 'Roy' as text shows.]
  7. ^ Brian Jenkinson, Sammes, A. J. (2000). Forensic Computing: A Practitioner's Guide (Practitioner Series). Berlin: Springer. pp. 157. ISBN 1-85233-299-9. "...only 2^12 (that is, 4096) allocation units or clusters can be addressed. In fact, the number is less than this, since 000h and 001h are not used and FF0h to FFFh are reserved or used for other purposes, leaving 002h to FEFh (2 to 4079) as the range of possible clusters." 
  8. ^ Andries Brouwer. "FAT Under Linux". http://www.win.tue.nl/~aeb/linux/fs/fat/fat-2.html.  Linux source code related to DOS often contains: #define MSDOS_FAT12 4084 (see line 76 of "KernelAPI: msdos_fs.h". http://www.kernel-api.org/docs/online/2.2.26/dc/dd8/msdos__fs_8h-source.html. ).
  9. ^ File allocation is specified using binary meanings for K (10241 instead of 10001), M (10242 instead of 10002), G (10243 instead of 10003), ...
  10. ^ "MS-DOS History". http://www.nukesoft.co.uk/msdos/dosversions.shtml. 
  11. ^ Microsoft Knowledge Base article: "MS-DOS Partitioning Summary"
  12. ^ "Errors Creating Files or Folders in the Root Directory". Microsoft Help and Support. December 16, 2004. http://support.microsoft.com/kb/120138. Retrieved 2006-10-14. 
  13. ^ "mkdosfs man page". http://www.die.net/doc/linux/man/man8/mkdosfs.8.html. 
  14. ^ a b "Limitations of FAT32 File System". Microsoft Help and Support. 2004-12-16. http://support.microsoft.com/kb/184006/en-us. Retrieved 2006-10-14. 
  15. ^ "Fdisk Does Not Recognize Full Size of Hard Disks Larger than 64 GB". Microsoft Help and Support. 2007-01-27. http://support.microsoft.com/kb/263044. Retrieved 2007-03-08. 
  16. ^ Fdisk.exe Unable to Partition Drives Larger Than 512 Gigabytes
  17. ^ "Limitations of the FAT32 File System in Windows XP". Microsoft Help and Support. 2002-09-04. http://support.microsoft.com/kb/314463/en-us. Retrieved 2007-01-24. 
  18. ^ a b Chen, Raymond (2006). Microsoft TechNet: A Brief and Incomplete History of FAT32. TechNet Magazine July 2006.
  19. ^ Fat32Format - Windows program for formatting disks as FAT32 beyond the 32 GB limit.
  20. ^ "Windows XP/2000 FAT32 Formatting Limit". allensmith.net. http://www.allensmith.net/Storage/HDDlimit/FAT32.htm. Retrieved 2007-04-08. 
  21. ^ "Release notes for v2.5.7". The Linux Kernel archives. 2002-03-12. http://www.kernel.org/pub/linux/kernel/v2.5/ChangeLog-2.5.7. Retrieved 2006-10-14. 
  22. ^ "fat32format". Ridgecrop Consultants Ltd. http://www.ridgecrop.demon.co.uk/index.htm?fat32format.htm. Retrieved 2009-11-16. 
  23. ^ Bob Eager (2000-10-28). "Implementation of extended attributes on the FAT file system". Tavi OS/2 pages. http://www.tavi.co.uk/os2pages/eadata.html. Retrieved 2006-10-14. 
  24. ^ "Update for Windows XP (KB955704)". Microsoft. http://www.microsoft.com/downloads/details.aspx?FamilyID=1cbe3906-ddd1-4ca2-b727-c2dff5e30f61&displaylang=en. Retrieved 2010-01-07. 
  25. ^ Brandon LeBlanc (2007-08-28). "Vista SP1 Whitepaper". Microsoft. http://windowsvistablog.com/blogs/windowsvista/pages/windows-vista-service-pack-1-beta-whitepaper.aspx#_Toc175944550. Retrieved 2007-08-28. 
  26. ^ Matthias Paul (2002-02-20). "Need DOS 6.22 (Not OEM)". alt.msdos.programmer. http://groups.google.com/group/alt.msdos.programmer/msg/6b10a1ea602e61e. Retrieved 2006-10-14. 
  27. ^ Wally Bass (1994-02-14). "Cluster Size". comp.os.msdos.programmer. http://groups.google.co.uk/group/comp.os.msdos.programmer/msg/79de2d76832cfbd6. Retrieved 2006-10-14. 
  28. ^ a b c Microsoft MS-DOS Programmer's Reference : version 5.0. Microsoft press. 1991. ISBN 1-55615-329-5. 
  29. ^ a b "Detailed Explanation of FAT Boot Sector". http://support.microsoft.com/kb/140418. Retrieved 2008-11-21. 
  30. ^ "Detailed Explanation of FAT Boot Sector". DEW Associates Corporation. 2002. http://www.dewassoc.com/kbase/hard_drives/boot_sector.htm. Retrieved 2009-02-15. 
  31. ^ Andries E. Brouwer (2002-09-20). "The FAT filesystem". http://www.win.tue.nl/~aeb/linux/fs/fat/fat-1.html. Retrieved 2006-10-14. 
  32. ^ a b vinDaci (1998-01-06). "Long Filename Specification". http://www.teleport.com/~brainy/lfn.htm. Retrieved 2007-03-13. 
  33. ^ "mount(8): mount file system – Linux man page". http://linux.die.net/man/8/mount. 
  34. ^ http://www.microsoft.com/presspass/press/2003/dec03/12-03ExpandIPPR.mspx
  35. ^ "Intellectual Property Licensing – FAT File System". Microsoft. http://www.microsoft.com/iplicensing/productDetail.aspx?productTitle=FAT%20File%20System. 
  36. ^ "At PUBPAT's request, patent office rejects Microsoft's FAT patent: Government Relies Heavily on Evidence Submitted by PUBPAT". Public Patent Foundation. 2004-09-30. http://www.pubpat.org/Microsoft_517_Rejected.htm. Retrieved 2006-10-14. 
  37. ^ Ina Fried (2004-09-30). "Microsoft FAT patent falls flat". CNET News. http://news.com.com/Microsoft+FAT+patent+falls+flat/2100-1014_3-5390138.html. Retrieved 2006-10-14. 
  38. ^ Andrew Orlowski (2005-10-05). "Microsoft FAT patent rejected - again". The Register. http://www.regdeveloper.co.uk/2005/10/05/microsoft_patent/. Retrieved 2006-10-14. 
  39. ^ "Patent Office rejects two Microsoft FAT patents". out-law.com. 2005-06-10. http://www.out-law.com/default.aspx?page=6202. Retrieved 2006-10-14. 
  40. ^ Andrew Orlowski (2004-06-14). "Microsoft's war on GPL dealt patent setback". The Register. http://www.theregister.co.uk/2004/06/14/ms_fat_patent_reexamined/. Retrieved 2006-10-14. 
  41. ^ Anne Broache (2006-01-10). "Microsoft's file system patent upheld". CNET News. http://news.com.com/Microsofts+file+system+patent+upheld/2100-1012_3-6025447.html. Retrieved 2006-10-14. 
  42. ^ Paul, Ryan (2009-02-25). "Microsoft suit over FAT patents could open OSS Pandora's Box". arstechnica.com. http://arstechnica.com/microsoft/news/2009/02/microsoft-sues-tomtom-over-fat-patents-in-linux-based-device.ars. Retrieved 2009-02-28. 
  43. ^ Fried, Ina (2009-03-30). "Microsoft, TomTom settle patent dispute". cnet.com. http://news.cnet.com/8301-13860_3-10206988-56.html. Retrieved 2009-08-22. 
  44. ^ Brown, Eric (2009-07-02). "Can FAT patch avoid Microsoft lawsuits?". DesktopLinux.Com. http://www.desktoplinux.com/news/NS4980952387.html?kc=rss. Retrieved 2009-08-23. 

External links


Citable sentences

Up to date as of December 30, 2010

Here are sentences from other pages on File Allocation Table, which are similar to those in the above article.








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