NT File System ( NTFS ) (commonly called New Technology File System ) is a proprietary journaling file system developed by Microsoft in the 1990s.
100-419: It was developed to overcome scalability, security and other limitations with FAT . NTFS adds several features that FAT and HPFS lack, including: access control lists (ACLs); filesystem encryption; transparent compression; sparse files ; file system journaling and volume shadow copy , a feature that allows backups of a system while in use. Starting with Windows NT 3.1 , it is the default file system of
200-561: A BPB with 32-bit entry for the number of sectors, as introduced since DOS 3.31 (see FAT16B below), keeping the cluster size and reducing the logical sector size in the BPB down to 512 bytes, while at the same time increasing the counts of logical sectors per cluster, reserved logical sectors, total logical sectors, and logical sectors per FAT by the same factor. A parallel development in MS-DOS / PC DOS which allowed an increase in
300-537: A Linux kernel driver by Szabolcs Szakacsits. It was re-written as a FUSE program to work on other systems that FUSE supports like macOS , FreeBSD, NetBSD, OpenBSD , Solaris, QNX , and Haiku and allows reading and writing to NTFS partitions. A performance enhanced commercial version of NTFS-3G, called " Tuxera NTFS for Mac", is also available from the NTFS-3G developers. Captive NTFS , a 'wrapping' driver that uses Windows' own driver ntfs.sys , exists for Linux. It
400-570: A company, so that its managers get to know when someone tries to delete them or make a copy of them, and whether they succeed. Encrypting File System (EFS) provides user-transparent encryption of any file or folder on an NTFS volume. EFS works in conjunction with the EFS service, Microsoft's CryptoAPI and the EFS File System Run-Time Library (FSRTL). EFS works by encrypting a file with a bulk symmetric key (also known as
500-445: A compressed file on an NTFS volume with a 4 KB (default) cluster (block) size. This reasonable maximum size decreases sharply for volumes with smaller cluster sizes. Large compressible files become highly fragmented since every chunk smaller than 64 KB becomes a fragment. Flash memory, such as SSD drives do not have the head movement delays and high access time of mechanical hard disk drives , so fragmentation has only
600-527: A confusing compatibility situation. Prior to 1995, versions of DOS accessed the disk via CHS addressing only. When Windows 95 (MS-DOS 7.0) introduced LBA disk access, partitions could start being physically located outside the first c. 8 GB of this disk and thereby out of the reach of the traditional CHS addressing scheme. Partitions partially or fully located beyond the CHS barrier therefore had to be hidden from non-LBA-enabled operating systems by using
700-472: A contiguous area of disk storage. Each entry contains either the number of the next cluster in the file, or else a marker indicating the end of the file, unused disk space, or special reserved areas of the disk. The root directory of the disk contains the number of the first cluster of each file in that directory. The operating system can then traverse the FAT, looking up the cluster number of each successive part of
800-476: A deeply esoteric method of tracking browsing history with concomitant privacy risks. If the downloaded file is executable (e.g. an installer), the Zone ADS can be used for reflection , enabling the program to identify where it was downloaded from, which may occasionally be used for telemetry and/or security purposes, whereby a program can attempt to verify that it was downloaded from an official source (assuming
900-851: A few hundred bytes in size. As MS-DOS 3.0 formatted all 16 MB-32 MB partitions in the FAT16 format, a 20 MB hard disk formatted under MS-DOS 3.0 was not accessible by MS-DOS 2.0. MS-DOS 3.0 to MS-DOS 3.30 could still access FAT12 partitions under 15 MB, but required all 16 MB-32 MB partitions to be FAT16, and so could not access MS-DOS 2.0 partitions in this size range. MS-DOS 3.31 and higher could access 16 MB-32 MB FAT12 partitions again. MS-DOS and PC DOS implementations of FAT12 and FAT16 could not access disk partitions larger than 32 megabytes. Several manufacturers developed their own FAT variants within their OEM versions of MS-DOS. Some vendors ( AST and NEC ) supported eight , instead of
1000-410: A few values reserved to indicate unallocated space or the end of a list) and the size of the disk cluster. Even if only one byte of storage is needed to extend a file, an entire cluster must be allocated to it. As a result, large numbers of small files can result in clusters being allocated that may contain mostly "empty" data to meet the minimum cluster size. Originally designed as an 8-bit file system,
1100-409: A file has multiple names via hard links, updating a file via one name does not update the cached data associated with the other name. You can always obtain up-to-date data using GetFileInformationByHandle (which is the true equivalent of POSIX stat function). This can be done using a handle which has no access to the file itself (passing zero to CreateFile for dwDesiredAccess), and closing this handle has
SECTION 10
#17327905069931200-406: A formatted capacity of 160 KB (FAT ID 0xFE ) for single-sided 5.25-inch floppy drives, and PC DOS 1.1 added support for a double-sided format with 320 KB (FAT ID 0xFF ). PC DOS 2.0 introduced support for 9-sector floppy formats with 180 KB (FAT ID 0xFC ) and 360 KB (FAT ID 0xFD ). 86-DOS 1.00 and PC DOS 1.0 directory entries included only one date,
1300-544: A hidden file called " EA␠DATA.␠SF " in the root directory of the FAT12 or FAT16 volume. This file is indexed by two previously reserved bytes in the file's (or directory's) directory entry at offset 0x14 . In the FAT32 format, these bytes hold the upper 16 bits of the starting cluster number of the file or directory, hence making it impossible to store OS/2 EAs on FAT32 using this method. However,
1400-567: A joint project to create the next generation of graphical operating system ; the result was OS/2 and HPFS . Because Microsoft disagreed with IBM on many important issues, they eventually separated; OS/2 remained an IBM project and Microsoft worked to develop Windows NT and NTFS. The HPFS file system for OS/2 contained several important new features. When Microsoft created their new operating system, they borrowed many of these concepts for NTFS. The original NTFS developers were Tom Miller , Gary Kimura, Brian Andrew, and David Goebel. Probably as
1500-510: A logical file system with 8.3 filenames and makes the use of either FAT12, FAT16, FAT32 or exFAT mandatory for its physical layer for compatibility. The file system uses an index table stored on the device to identify chains of data storage areas associated with a file, the File Allocation Table ( FAT ). The FAT is statically allocated at the time of formatting. The table is a linked list of entries for each cluster ,
1600-528: A new NTFS implementation for Mac OS X 10.6 . Native NTFS write support is included in 10.6 and later, but is not activated by default, although workarounds do exist to enable the functionality. However, user reports indicate the functionality is unstable and tends to cause kernel panics . Paragon Software Group sells a read-write driver named NTFS for Mac , which is also included on some models of Seagate hard drives. The NetDrive package for OS/2 (and derivatives such as eComStation and ArcaOS ) supports
1700-599: A new feature in the file system; all the others are new operating system features that make use of NTFS features already in place. NTFS is optimized for 4 KB clusters , but supports a maximum cluster size of 2 MB . (Earlier implementations support up to 64 KB) The maximum NTFS volume size that the specification can support is 2 − 1 clusters, but not all implementations achieve this theoretical maximum, as discussed below. The maximum NTFS volume size implemented in Windows XP Professional
1800-690: A partition type 07 must perform additional checks to distinguish between HPFS and NTFS. Microsoft has released five versions of NTFS: The NTFS.sys version number (e.g. v5.0 in Windows 2000) is based on the operating system version; it should not be confused with the NTFS version number (v3.1 since Windows XP). Although subsequent versions of Windows added new file system-related features, they did not change NTFS itself. For example, Windows Vista implemented NTFS symbolic links , Transactional NTFS , partition shrinking, and self-healing. NTFS symbolic links are
1900-430: A plugin which allows read and write access to NTFS volumes. There is a free-for-personal-use read/write driver for MS-DOS by Avira called "NTFS4DOS". Ahead Software developed a "NTFSREAD" driver (version 1.200) for DR-DOS 7.0x between 2002 and 2004. It was part of their Nero Burning ROM software. NTFS uses access control lists and user-level encryption to help secure user data. In NTFS, each file or folder
2000-473: A potential hiding place for malware, spyware, unseen browser history, and other potentially unwanted information. Alternate streams are not listed in Windows Explorer, and their size is not included in the file's size. When the file is copied or moved to another file system without ADS support the user is warned that alternate data streams cannot be preserved. No such warning is typically provided if
2100-499: A pre-installed tool to convert a FAT file system into NTFS directly without the need to rewrite all files, though this cannot be reversed easily. The FAT file system is used in removable media such as floppy disks , super-floppies , memory and flash memory cards or USB flash drives . FAT is supported by portable devices such as PDAs , digital cameras , camcorders , media players , and mobile phones. The DCF file system adopted by almost all digital cameras since 1998 defines
SECTION 20
#17327905069932200-505: A regular hard link. The NTFS file system has a limit of 1024 hard links on a file. Alternate data streams allow more than one data stream to be associated with a filename (a fork ), using the format "filename:streamname" (e.g., "text.txt:extrastream"). These streams are not shown to or made editable by users through any typical GUI application built into Windows by default, disguising their existence from most users. Although intended for helpful metadata , their arcane nature makes them
2300-404: A result of this common ancestry, HPFS and NTFS use the same disk partition identification type code (07). Using the same Partition ID Record Number is highly unusual, since there were dozens of unused code numbers available, and other major file systems have their own codes. For example, FAT has more than nine (one each for FAT12 , FAT16 , FAT32 , etc.). Algorithms identifying the file system in
2400-449: A series of discussions between McDonald and Bill Gates . It was introduced with 8-bit table elements (and valid data cluster numbers up to 0xBF ) in a precursor to Microsoft 's Standalone Disk BASIC-80 for an 8080 -based successor of the NCR 7200 model VI data-entry terminal, equipped with 8-inch (200 mm) floppy disks, in 1977 or 1978. In 1978, Standalone Disk BASIC-80
2500-489: A smaller penalty. If system files that are needed at boot time (such as drivers, NTLDR, winload.exe, or BOOTMGR) are compressed, the system may fail to boot correctly, because decompression filters are not yet loaded. Later editions of Windows do not allow important system files to be compressed. Since Windows 10 , Microsoft has introduced new file compression scheme based on the XPRESS algorithm with 4K/8K/16K block size and
2600-602: A special mark byte indicating the presence of extended attributes to help speed up things. (This extension is critically incompatible with the FAT32+ method to store files larger than 4 GB minus 1 on FAT32 volumes.) Extended attributes are accessible via the Workplace Shell desktop, through REXX scripts, and many system GUI and command-line utilities (such as 4OS2 ). Unified Extensible Firmware Interface Too Many Requests If you report this error to
2700-405: A system with Unified Extensible Firmware Interface (UEFI) and 64-bit support. GPT data disks are supported on systems with BIOS. The NTFS maximum theoretical limit on the size of individual files is 16 EB ( 16 × 1024 or 2 bytes ) minus 1 KB, which totals 18,446,744,073,709,550,592 bytes. With Windows 10 version 1709 and Windows Server 2019 , the maximum implemented file size
2800-519: A user holding administrative privileges. Windows Vista adds mandatory access control info to DACLs. DACLs are the primary focus of User Account Control in Windows Vista and later. The second ACL, called system access control list (SACL), defines which interactions with the file or folder are to be audited and whether they should be logged when the activity is successful, failed or both. For example, auditing can be enabled on sensitive files of
2900-464: A user-friendly way. NTFS Streams were introduced in Windows NT 3.1 , to enable Services for Macintosh (SFM) to store resource forks . Although current versions of Windows Server no longer include SFM, third-party Apple Filing Protocol (AFP) products (such as GroupLogic 's ExtremeZ-IP) still use this feature of the file system. Compression is enabled on a per-folder or per-file basis by setting
3000-471: Is 2 − 1 clusters, partly due to partition table limitations. For example, using 64 KB clusters, the maximum size Windows XP NTFS volume is 256 TB minus 64 KB . Using the default cluster size of 4 KB, the maximum NTFS volume size is 16 TB minus 4 KB. Both of these are vastly higher than the 128 GB limit in Windows XP SP1 . The size of a partition in
3100-439: Is 4 GB minus 1 byte, or 4,294,967,295 (2 − 1) bytes. This limit is a consequence of the 4-byte file length entry in the directory table and would also affect relatively huge FAT16 partitions enabled by a sufficient sector size. Like FAT12 and FAT16, FAT32 does not include direct built-in support for long filenames, but FAT32 volumes can optionally hold VFAT long filenames in addition to short filenames in exactly
NTFS - Misplaced Pages Continue
3200-495: Is 8 PB minus 2 MB or 9,007,199,252,643,840 bytes. While the different NTFS versions are for the most part fully forward - and backward-compatible , there are technical considerations for mounting newer NTFS volumes in older versions of Microsoft Windows. This affects dual-booting, and external portable hard drives. For example, attempting to use an NTFS partition with "Previous Versions" ( Volume Shadow Copy ) on an operating system that does not support it will result in
3300-453: Is a file system developed for personal computers and was the default filesystem for the MS-DOS and Windows 9x operating systems. Originally developed in 1977 for use on floppy disks , it was adapted for use on hard disks and other devices. The increase in disk drive capacity over time drove modifications to the design that resulted in versions: FAT12 , FAT16 , FAT32 , and exFAT . FAT
3400-472: Is a journaling file system and uses the NTFS Log ( $ LogFile ) to record metadata changes to the volume. It is a feature that FAT does not provide and is critical for NTFS to ensure that its complex internal data structures will remain consistent in case of system crashes or data moves performed by the defragmentation API, and allow easy rollback of uncommitted changes to these critical data structures when
3500-529: Is added by Internet Explorer and by most browsers to mark files downloaded from external sites as possibly unsafe to run; the local shell would then require user confirmation before opening them. When the user indicates that they no longer want this confirmation dialog, this ADS is deleted. This functionality is also known as " Mark of the Web ". Without deep modifications to the source code, all Chromium (e.g. Google Chrome ) and Firefox -based web browsers also write
3600-561: Is also named FAT32X in order to indicate usage of LBA disk access instead of CHS. On such partitions, CHS-related geometry entries, namely the CHS sector addresses in the MBR as well as the number of sectors per track and the number of heads in the EBPB record, may contain no or misleading values and should not be used. OS/2 heavily depends on extended attributes (EAs) and stores them in
3700-497: Is assigned a security descriptor that defines its owner and contains two access control lists (ACLs). The first ACL, called discretionary access control list (DACL), defines exactly what type of interactions (e.g. reading, writing, executing or deleting) are allowed or forbidden by which user or groups of users. For example, files in the C:\Program Files folder may be read and executed by all users but modified only by
3800-421: Is determined when the volume is formatted, and is stored in a 16-bit field. For a given number RDE and sector size SS , the number RDS of root directory sectors is RDS = ceil((RDE × 32) / SS) , and RDE is normally chosen to fill these sectors, i.e., RDE × 32 = RDS × SS . FAT12 and FAT16 media typically use 512 root directory entries on non-floppy media. Some third-party tools, like mkdosfs, allow
3900-448: Is known as FAT16B . Since older versions of DOS were not designed to cope with more than 65,535 sectors, it was necessary to introduce a new partition type for this format in order to hide it from pre-3.31 issues of DOS. The original form of FAT16 (with less than 65,536 sectors) had a partition type 0x04 . To deal with disks larger than this, type 0x06 was introduced to indicate 65,536 or more sectors. In addition to this,
4000-509: Is proportionally larger. Much later, Windows NT increased the maximum cluster size to 64 KB, by considering the sectors-per-cluster count as unsigned. However, the resulting format was not compatible with any other FAT implementation of the time, and it generated greater internal fragmentation . Windows 98 , SE and ME also supported reading and writing this variant, but its disk utilities did not work with it and some FCB services are not available for such volumes. This contributes to
4100-549: Is used on floppy disks, FAT16 and FAT32 are typically found on the larger media. FAT is used internally for the EFI system partition in the boot stage of EFI -compliant computers. Hidden FAT filesystems are also used in the UEFI boot partition on modern PCs. FAT is still used in drives expected to be used by multiple operating systems, such as in shared Windows, Linux and DOS environments. Microsoft Windows additionally comes with
NTFS - Misplaced Pages Continue
4200-456: The $ LogFile by versions of Windows older than 8.0 results in an unnecessary invocation of the CHKDSK disk repair utility. This is particularly a concern in a multi-boot scenario involving pre- and post-8.0 versions of Windows, or when frequently moving a storage device between older and newer versions. A Windows Registry setting exists to prevent the automatic upgrade of the $ LogFile to
4300-516: The $ LogFile . Backward compatibility is provided by downgrading the $ LogFile to version 1.1 when an NTFS volume is cleanly dismounted. It is again upgraded to version 2.0 when mounting on a compatible version of Windows. However, when hibernating to disk in the logoff state (a.k.a. Hybrid Boot or Fast Boot, which is enabled by default), mounted file systems are not dismounted, and thus the $ LogFile s of any active file systems are not downgraded to version 1.1. The inability to process version 2.0 of
4400-477: The Zone.Identifier stream to downloaded files. As of Windows 10, the contents of the Zone.Identifer stream are structured like an INI file (i.e. a key-value store ) that includes the keys HostIpAddress , HostUrl , and ReferrerUrl . To some extent, these are implementation-defined fields, but they typically contain the domain name and exact URL of the original online download location, potentially offering
4500-449: The LZX algorithm; both are variants of LZ77 updated with Huffman entropy coding and range coding , which LZNT1 lacked. These compression algorithms were taken from Windows Imaging Format (WIM file). The new compression scheme is used by CompactOS feature, which reduces disk usage by compressing Windows system files. CompactOS is not an extension of NTFS file compression and does not use
4600-577: The Windows NT family superseding the File Allocation Table (FAT) file system. NTFS read/write support is available on Linux and BSD using NTFS3 in Linux and NTFS-3G in BSD . NTFS uses several files hidden from the user to store metadata about other files stored on the drive which can help improve speed and performance when reading data. In the mid-1980s, Microsoft and IBM formed
4700-493: The Windows NT platform in 1993, but FAT remained the standard for the home user until the introduction of Windows XP in 2001. Windows Me was the final version of Windows to use FAT as its default file system. For floppy disks, FAT has been standardized as ECMA -107 and ISO / IEC 9293:1994 (superseding ISO 9293:1987 ). These standards cover FAT12 and FAT16 with only short 8.3 filename support; long filenames with VFAT were partially patented . While FAT12
4800-465: The command prompt , PowerShell or third-party tools, or by formatting the volume on a non-Windows system or on a Windows 9x system with FAT32 support and then transferring it to the Windows NT system. In August 2024, Microsoft released an update to Windows 11 preview builds that allows for the creation of FAT32 partitions up to 2TB in size. The maximal possible size for a file on a FAT32 volume
4900-509: The physical sector size (still 512 bytes) on the disk. The DOS-BIOS or System BIOS would then combine multiple physical sectors into logical sectors for the file system to work with. These changes were transparent to the file system implementation in the DOS kernel. The underlying DOS-BIOS translated these logical sectors into physical sectors according to partitioning information and the drive's physical geometry. The drawback of this approach
5000-444: The 'compressed' attribute. When compression is enabled on a folder, any files moved or saved to that folder will be automatically compressed using LZNT1 algorithm (a variant of LZ77 ). The compression algorithm is designed to support cluster sizes of up to 4 KB; when the cluster size is greater than 4 KB on an NTFS volume, NTFS compression is not available. Data is compressed in 16-cluster chunks (up to 64 KB in size); if
5100-518: The 'compressed' attribute; instead, it sets a reparse point on each compressed file with a WOF (Windows Overlay Filter) tag, but the actual data is stored in an alternate data stream named "WofCompressedData", which is decompressed on-the-fly by a WOF filesystem filter driver, and the main file is an empty sparse file . This design is meant purely for read-only access, so any writes to compressed files result in an automatic decompression. File Allocation Table File Allocation Table ( FAT )
SECTION 50
#17327905069935200-529: The 16-bit disk sector count to 32 bits in the BPB. 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 result was initially called the DOS 3.31 Large File System . Microsoft 's DSKPROBE tool refers to type 0x06 as BigFAT , whereas some older versions of FDISK described it as BIGDOS . Technically, it
5300-516: The FATs. FAT12 remains in use on all common floppy disks , including 1.44 MB and later 2.88 MB disks (media descriptor byte 0xF0 ). In 1984, IBM released the PC AT , which required PC DOS 3.0 to access its 20 MB hard disk. Microsoft introduced MS-DOS 3.0 in parallel. Cluster addresses were increased to 16-bit, allowing for up to 65,526 clusters per volume. However,
5400-500: The File Encryption Key, or FEK), which is used because it takes a relatively small amount of time to encrypt and decrypt large amounts of data than if an asymmetric key cipher is used. The symmetric key that is used to encrypt the file is then encrypted with a public key that is associated with the user who encrypted the file, and this encrypted data is stored in an alternate data stream of the encrypted file. To decrypt
5500-483: The Master Boot Record (MBR) is limited to 2 TiB with a hard drive with 512-byte physical sectors, although for a 4 KiB physical sector the MBR partition size limit is 16 TiB. An alternative is to use multiple GUID Partition Table (GPT or "dynamic") volumes for be combined to create a single NTFS volume larger than 2 TiB. Booting from a GPT volume to a Windows environment in a Microsoft supported way requires
5600-547: The Windows NT line, native support for FAT32 arrived in Windows 2000 . A free FAT32 driver for Windows NT 4.0 was available from Winternals , a company later acquired by Microsoft. The acquisition of the driver from official sources is no longer possible. Since 1998, Caldera's dynamically loadable DRFAT32 driver could be used to enable FAT32 support in DR-DOS. The first version of DR-DOS to natively support FAT32 and LBA access
5700-498: The cluster number. The FAT32 boot sector uses a 32-bit field for the sector count, limiting the maximal FAT32 volume size to 2 terabytes with a sector size of 512 bytes . The maximum FAT32 volume size is 16 TB with a sector size of 4,096 bytes. The built-in Windows shell disk format tool on Windows NT arbitrarily only supports volume sizes up to 32 GB, but Windows supports reading and writing to preexisting larger FAT32 volumes, and these can be created with
5800-712: The compression reduces 64 KB of data to 60 KB or less, NTFS treats the unneeded 4 KB pages like empty sparse file clusters—they are not written. This allows for reasonable random-access times as the OS merely has to follow the chain of fragments. Compression works best with files that have repetitive content, are seldom written, are usually accessed sequentially, and are not themselves compressed. Single-user systems with limited hard disk space can benefit from NTFS compression for small files, from 4 KB to 64 KB or more, depending on compressibility. Files smaller than approximately 900 bytes are stored within
5900-463: The contents of a directory using FindFirstFile/FindNextFile family of APIs, (equivalent to the POSIX opendir/readdir APIs) you will also receive this cached information, in addition to the name and inode. However, you may not see up-to-date information, as this information is only guaranteed to be updated when a file is closed, and then only for the directory from which the file was opened. This means where
6000-619: The contents of those previous versions being lost. A Windows command-line utility called convert.exe can convert supporting file systems to NTFS, including HPFS (only on Windows NT 3.1, 3.5, and 3.51), FAT16 and FAT32 (on Windows 2000 and later). FreeBSD 3.2 released in May 1999 included read-only NTFS support written by Semen Ustimenko. This implementation was ported to NetBSD by Christos Zoulas and Jaromir Dolecek and released with NetBSD 1.5 in December 2000. The FreeBSD implementation of NTFS
6100-526: The directory entry of the MFT . Users of fast multi-core processors will find improvements in application speed by compressing their applications and data as well as a reduction in space used. Even when SSD controllers already compress data, there is still a reduction in I/Os since less data is transferred. According to research by Microsoft's NTFS Development team, 50–60 GB is a reasonable maximum size for
SECTION 60
#17327905069936200-515: The disk driver was expanded to cope with more than 65,535 sectors as well. The only other difference between the original FAT16 and the newer FAT16B format is the usage of a newer BPB format with 32-bit sector entry. Therefore, newer operating systems supporting the FAT16B format can cope also with the original FAT16 format without any necessary changes. If partitions to be used by pre-DOS 3.31 issues of DOS need to be created by modern tools,
6300-403: The disk file as a cluster chain until the end of the file is reached. Sub-directories are implemented as special files containing the directory entries of their respective files. Each entry in the FAT linked list is a fixed number of bits: 12, 16 or 32. The maximum size of a file or a disk drive that can be accessed is the product of the largest number that can be stored in the entries (less
6400-415: The file data area. Clusters containing bad sectors were marked unusable with the reserved value 0xFF7 in the FAT. While 86-DOS supported three disk formats (250.25 KB, 616 KB and 1232 KB, with FAT IDs 0xFF and 0xFE ) on 8-inch (200 mm) floppy drives, IBM PC DOS 1.0 , released with the original IBM Personal Computer in 1981, supported only an 8-sector floppy format with
6500-432: The file is attached to an e-mail, or uploaded to a website. Thus, using alternate streams for critical data may cause problems. Microsoft provides a downloadable tool called Streams to view streams on a selected volume. Starting with Windows PowerShell 3.0, it is possible to manage ADS natively with six cmdlets: Add-Content, Clear-Content, Get-Content, Get-Item, Remove-Item, Set-Content. A small ADS named Zone.Identifier
6600-423: The file, the file system uses the private key of the user to decrypt the symmetric key that is stored in the data stream. It then uses the symmetric key to decrypt the file. Because this is done at the file system level, it is transparent to the user. Also, in case of a user losing access to their key, support for additional decryption keys has been built into the EFS system, so that a recovery agent can still access
6700-484: The files if needed. NTFS-provided encryption and NTFS-provided compression are mutually exclusive; however, NTFS can be used for one and a third-party tool for the other. The support of EFS is not available in Basic, Home, and MediaCenter versions of Windows, and must be activated after installation of Professional, Ultimate, and Server versions of Windows or by using enterprise deployment tools within Windows domains. NTFS
6800-414: The incidental effect of updating the cached information. Windows uses hard links to support short (8.3) filenames in NTFS. Operating system support is needed because there are legacy applications that can work only with 8.3 filenames, but support can be disabled. In this case, an additional filename record and directory entry is added, but both 8.3 and long file name are linked and updated together, unlike
6900-524: The last modified date. PC DOS 1.1 added the last modified time. PC DOS 1.x file attributes included a hidden bit and system bit, with the remaining six bits undefined. At this time, DOS did not support sub-directories, but typically there were only a few dozen files on a diskette . The PC XT was the first PC with an IBM-supplied hard drive, and PC DOS 2.0 supported that hard drive with FAT12 ( FAT ID 0xF8 ). The fixed assumption of 8 sectors per clusters on hard disks practically limited
7000-399: The maximum number of clusters must increase as disk drive capacity increases, and so the number of bits used to identify each cluster has grown. The successive major variants of the FAT format are named after the number of table element bits: 12 ( FAT12 ), 16 ( FAT16 ), and 32 ( FAT32 ). There are several variants of the FAT file system (e.g. FAT12 , FAT16 and FAT32 ). FAT16 refers to both
7100-489: The maximum partition size to 16 MB for 512 byte sectors and 4 KB clusters. The BIOS Parameter Block ( BPB ) was introduced with PC DOS 2.0 as well, and this version also added read-only, archive , volume label , and directory attribute bits for hierarchical sub-directories. MS-DOS 3.0 introduced support for high-density 1.2 MB 5.25-inch diskettes (media descriptor 0xF9 ), which notably had 15 sectors per track, hence more space for
7200-483: The maximum possible FAT size was the introduction of multiple FAT partitions on a hard disk. To allow the use of more FAT partitions in a compatible way, a new partition type was introduced in PC ;DOS 3.2 (1986), the extended partition (EBR), which is a container for an additional partition called logical drive . Since PC DOS 3.3 (April 1987), there is another, optional extended partition containing
7300-484: The maximum possible number of sectors and the maximum partition size of 32 MB did not change. Although cluster addresses were 16 bits, this format was not what today is commonly understood as FAT16 . A partition type 0x04 indicates this form of FAT16 with less than 65,536 sectors (less than 32 MB for sector size 512). The benefit of FAT16 was the use of smaller clusters, making disk usage more efficient, particularly for large numbers of files only
7400-457: The new partition type 0x0E in the partition table instead. FAT16 partitions using this partition type are also named FAT16X . The only difference, compared to previous FAT16 partitions, is the fact that some CHS-related geometry entries in the BPB record, namely the number of sectors per track and the number of heads, may contain no or misleading values and should not be used. The number of root directory entries available for FAT12 and FAT16
7500-535: The newer version. The problem can also be dealt with by disabling Hybrid Boot. The USN Journal (Update Sequence Number Journal) is a system management feature that records (in $ Extend\$ UsnJrnl ) changes to files, streams and directories on the volume, as well as their various attributes and security settings. The journal is made available for applications to track changes to the volume. This journal can be enabled or disabled on non-system volumes. The hard link feature allows different file names to directly refer to
7600-404: The next logical drive , and so on. The MBR of a hard disk can either define up to four primary partitions, or an extended partition in addition to up to three primary partitions. In November 1987, Compaq Personal Computer DOS 3.31 (a modified OEM version of MS-DOS 3.3 released by Compaq with their machines) introduced what today is simply known as the FAT16 format, with the expansion of
7700-621: The only criteria theoretically necessary to meet are a sector count of less than 65536, and the usage of the old partition ID ( 0x04 ). In practice however, type 0x01 and 0x04 primary partitions should not be physically located outside the first 32 MB of the disk, due to other restrictions in MS-DOS ;2.x, which could not cope with them otherwise. In 1988, the FAT16B improvement became more generally available through DR DOS 3.31, PC DOS 4.0, OS/2 1.1, and MS-DOS 4.0. The limit on partition size
7800-498: The original group of FAT file systems with 16-bit wide cluster entries and also to later variants. " VFAT " is an optional extension for long file names, which can work on top of any FAT file system. Volumes using VFAT long-filenames can be read also by operating systems not supporting the VFAT extension. The original FAT file system (or FAT structure , as it was called initially) was designed and implemented by Marc McDonald , based on
7900-498: The same file contents. Hard links may link only to files in the same volume, because each volume has its own MFT . Hard links were originally included to support the POSIX subsystem in Windows NT. Although hard links use the same MFT record ( inode ) which records file metadata such as file size, modification date, and attributes, NTFS also caches this data in the directory entry as a performance enhancement. This means that when listing
8000-419: The same way as VFAT long filenames have been optionally implemented for FAT12 and FAT16 volumes. FAT32 was introduced with Windows 95 OSR2(MS-DOS 7.1) in 1996, although reformatting was needed to use it, and DriveSpace 3 (the version that came with Windows 95 OSR2 and Windows 98) never supported it. Windows 98 introduced a utility to convert existing hard disks from FAT16 to FAT32 without loss of data. In
8100-570: The size of directory entries was 16 bytes in Standalone Disk BASIC , MIDAS instead occupied 32 bytes per entry. Tim Paterson of Seattle Computer Products (SCP) was first introduced to Microsoft's FAT structure when he helped Bob O'Rear adapting the Standalone Disk BASIC-86 emulator port onto SCP's S-100 bus 8086 CPU board prototype during a guest week at Microsoft in May 1979. The final product
8200-658: The specifications of the file system itself. Therefore, even if default issues of MS-DOS and PC DOS were not able to cope with them, most of these vendor-specific FAT12 and FAT16 variants can be mounted by more flexible file system implementations in operating systems such as DR-DOS, simply by changing the partition ID to one of the recognized types. Also, if they no longer need to be recognized by their original operating systems, existing partitions can be "converted" into FAT12 and FAT16 volumes more compliant with versions of MS-DOS/PC DOS 4.0–6.3, which do not support sector sizes different from 512 bytes, by switching to
8300-405: The standard four , primary partition entries in their custom extended Master Boot Record ( MBR ), and they adapted MS-DOS to use more than a single primary partition. Other vendors worked around the volume size limits imposed by the 16-bit sector entries by increasing the apparent size of the sectors the file system operated on. These logical sectors were larger (up to 8192 bytes) than
8400-551: The stream has not been removed or spoofed ) and can transmit the information back over the internet (an example of this in action is BiglyBT 's installer). Malware has used alternate data streams to hide code. Since the late 2000s, some malware scanners and other special tools check for alternate data streams. Due to the risks associated with ADS, particularly involving privacy and the Zone.Identifier stream, there exists software specifically designed to strip streams from files (certain streams with perceived risk or all of them) in
8500-605: The table elements to 12 bits , reduced the number of FATs to two, redefined the semantics of some of the reserved cluster values, and modified the disk layout, so that the root directory was now located between the FAT and the data area for his implementation of FAT12 . Paterson also increased the nine-character (6.3) filename length limit to eleven characters to support CP/M -style 8.3 filenames and File Control Blocks . The format used in Microsoft Standalone Disk BASIC's 8-bit file system precursor
8600-415: The third-party FAT32 installable file system (IFS) driver FAT32.IFS version 0.70 and higher by Henk Kelder & Netlabs for OS/2, eComStation and ArcaOS stores extended attributes in extra files with filenames having the string " ␠EA.␠SF " appended to the regular filename of the file to which they belong. The driver also utilizes the byte at offset 0x0C in directory entries to store
8700-504: The user to set this parameter. In order to overcome the volume size limit of FAT16, while at the same time allowing DOS real-mode code to handle the format, Microsoft designed a new version of the file system, FAT32 , which supported an increased number of possible clusters, but could reuse most of the existing code, so that the conventional memory footprint was increased by less than 5 KB under DOS. Cluster values are represented by 32-bit numbers, of which 28 bits are used to hold
8800-573: The volume is remounted. Notably affected structures are the volume allocation bitmap, modifications to MFT records such as moves of some variable-length attributes stored in MFT records and attribute lists, and indices for directories and security descriptors . The ( $ LogFile ) format has evolved through several versions: The incompatibility of the $ LogFile versions implemented by Windows 8 , Windows 10 , Windows 11 prevents Windows 7 (and earlier versions of Windows) from recognizing version 2.0 of
8900-449: Was OEM DR-DOS 7.04 in 1999. That same year IMS introduced native FAT32 support with REAL/32 7.90, and IBM 4690 OS added FAT32 support with version 2. Ahead Software provided another dynamically loadable FAT32.EXE driver for DR-DOS 7.03 with Nero Burning ROM in 2004. IBM introduced native FAT32 support with OEM PC DOS 7.1 in 1999. Two partition types have been reserved for FAT32 partitions, 0x0B and 0x0C . The latter type
9000-500: Was also ported to OpenBSD by Julien Bordet and offers native read-only NTFS support by default on i386 and amd64 platforms as of version 4.9 released 1 May 2011. Linux kernel versions 2.1.74 and later include a driver written by Martin von Löwis which has the ability to read NTFS partitions; kernel versions 2.5.11 and later contain a new driver written by Anton Altaparmakov ( University of Cambridge ) and Richard Russon which supports file read. The ability to write to files
9100-634: Was built as a Filesystem in Userspace (FUSE) program and released under the GPL but work on Captive NTFS ceased in 2006. Linux kernel versions 5.15 onwards carry NTFS3, a fully functional NTFS Read-Write driver which works on NTFS versions up to 3.1 and is maintained primarily by the Paragon Software Group . Mac OS X 10.3 included Ustimenko's read-only implementation of NTFS from FreeBSD. Then in 2006 Apple hired Anton Altaparmakov to write
9200-436: Was dictated by the 8-bit signed count of sectors per cluster, which originally 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 cluster size, thereby fixing the "definitive" limit for the FAT16 partition size at 2 GB for sector size 512. On magneto-optical media, which can have 1 or 2 KB sectors instead of 0.5 KB, this size limit
9300-416: Was dropped with MS-DOS 1.20 . FAT12 used 12-bit entries for the cluster addresses; some values were reserved to mark the end of a chain of clusters, to mark unusable areas of the disk, or for other purposes, so the maximum number of clusters was limited to 4078. To conserve disk space, two 12-bit FAT entries used three consecutive 8-bit bytes on disk, requiring manipulation to unpack the 12-bit values. This
9400-918: Was increased memory used for sector buffering and deblocking. Since older DOS versions could not use large logical sectors, the OEMs introduced new partition IDs for their FAT variants in order to hide them from off-the-shelf issues of MS-DOS and PC DOS. Known partition IDs for logical sectored FATs include: 0x08 ( Commodore MS-DOS 3.x), 0x11 ( Leading Edge MS-DOS 3.x), 0x14 (AST MS-DOS 3.x), 0x24 (NEC MS-DOS 3.30 ), 0x56 ( AT&T MS-DOS 3.x), 0xE5 ( Tandy MS-DOS), 0xF2 ( Sperry IT MS-DOS 3.x, Unisys MS-DOS 3.3 – also used by Digital Research DOS Plus 2.1). OEM versions like Toshiba MS-DOS, Wyse MS-DOS 3.2 and 3.3, as well as Zenith MS-DOS are also known to have utilized logical sectoring. While non-standard and sub-optimal, these FAT variants are perfectly valid according to
9500-412: Was introduced with kernel version 2.6.15 in 2006 which allows users to write to existing files but does not allow the creation of new ones. Paragon's NTFS driver (see below) has been merged into kernel version 5.15, and it supports read/write on normal, compressed and sparse files, as well as journal replaying. NTFS-3G is a free GPL -licensed FUSE implementation of NTFS that was initially developed as
9600-524: Was not supported by QDOS. By August 1980, QDOS had been renamed 86-DOS . Starting with 86-DOS 0.42 , the size and layout of directory entries was changed from 16 bytes to 32 bytes in order to add a file date stamp and increase the theoretical file size limit beyond the previous limit of 16 MB. 86-DOS 1.00 became available in early 1981. Later in 1981, 86-DOS evolved into Microsoft's MS-DOS and IBM PC DOS . The capability to read previously formatted volumes with 16-byte directory entries
9700-510: Was ported to the 8086 using an emulator on a DEC PDP-10 , since no real 8086 systems were available at this time. The FAT file system was also used in Microsoft's MDOS/MIDAS , an operating system for 8080/Z80 platforms written by McDonald since 1979. The Standalone Disk BASIC version supported three FATs, whereas this was a parameter for MIDAS. Reportedly, MIDAS was also prepared to support 10-bit, 12-bit and 16-bit FAT variants. While
9800-445: Was replaced with NTFS as the default file system on Microsoft operating systems starting with Windows XP . Nevertheless, FAT continues to be commonly used on relatively small capacity solid-state storage technologies such as SD card , MultiMediaCard (MMC) and eMMC because of its compatibility and ease of implementation. FAT was used on hard disks throughout the DOS and Windows 9x eras. Microsoft introduced NTFS with
9900-602: Was shown at Lifeboat Associates ' booth stand at the National Computer Conference in New York on June 4–7, 1979, where Paterson learned about the more sophisticated FAT implementation in MDOS/MIDAS and McDonald talked to him about the design of the file system. Between April and August 1980, while borrowing the FAT concept for SCP's own 8086 operating system QDOS 0.10 , Tim Paterson extended
10000-496: Was sufficient for the original floppy disk drives, and small hard disks up to 32 megabytes. The FAT16B version available with DOS 3.31 supported 32-bit sector numbers, and so increased the volume size limit. All the control structures fit inside the first track, to avoid head movement during read and write operations. Any bad sector in the control structures area would make the disk unusable. The DOS formatting tool rejected such disks completely. Bad sectors were allowed only in
#992007