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^IBM introduced JFS with the initial release of AIX Version 3.1 in 1990. This file system now called JFS1. The new JFS, ported from OS/2 to AIX and Linux, was first shipped in OS/2 Warp Server for e-Business in 1999. It was released as JFS2 on AIX 5L.
^Microsoft first introduced FAT32 in Windows 95 OSR2 (OEM Service Release 2) and then later in Windows 98. NT-based Windows did not have any support for FAT32 up to Windows NT4; Windows 2000 was the first NT-based Windows OS that received the ability to work with it.
^ abThese are the restrictions imposed by the on-disk directory entry structures themselves. Particular Installable File System drivers may place restrictions of their own on file and directory names; and particular and operating systems may also place restrictions of their own, across all filesystems. MS-DOS, Microsoft Windows, and OS/2 disallow the characters \ / : ? * " > < | and NUL in file and directory names across all filesystems. Unix-like systems disallow the characters / and NUL in file and directory names across all filesystems.
^ abcdeFor filesystems that have variable allocation unit (block/cluster) sizes, a range of size are given, indicating the maximum volume sizes for the minimum and the maximum possible allocation unit sizes of the filesystem (e.g. 512 bytes and 128 KB for FAT — which is the cluster size range allowed by the on-disk data structures, although some Installable File System drivers and operating systems do not support cluster sizes larger than 32 KB).
^ abcdefghijklmnopqrCite error: The named reference note-26 was invoked but never defined (see the help page).
^ abXFS has a limitation under Linux 2.4 of 64 TB file size, but Linux 2.4 only supports a maximum block size of 2 TB. This limitation is not present under IRIX.
^ abQFS allows files to exceed the size of disk when used with its integrated HSM, as only part of the file need reside on disk at any one time.
^Varies wildly according to block size and fragmentation of block allocation groups.
^Maximum combined filename/filetype length is 236 bytes; each component has an individual maximum length of 255 bytes.
^Maximum pathname length is 4,096 bytes, but quoted limits on individual components add up to 1,664 bytes.
^This restriction might be lifted in newer versions.
^NTFS access control lists can express any access policy possible using simple POSIX file permissions (and far more), but use of a POSIX-like interface is not supported without an add-on such as Services for UNIX or Cygwin.
^ abcdAccess-control lists and MAC labels are layered on top of extended attributes.
^Some operating systems implemented extended attributes as a layer over UFS1 with a parallel backing file (e.g., FreeBSD 4.x).
^ abcdefghiSome Installable File System drivers and operating systems may not support extended attributes, access control lists or security labels on these filesystems. Linux kernels prior to 2.6.x may either be missing support for these altogether or require a patch.
^Creation time is stored in the backing ext4 filesystem, but is not yet sent to clients.
^Lustre has checksums for data over the network, but depends on backing filesystem and hardware for checksums of persistent data
^ abcdefNot available with ext3/4, but will be available with ZFS OST/MDT backing filesystems.
^ocfs2 computes and validates checksums of metadata objects like inodes and directories. It also stores an error correction code capable to fixing single-bite errors.
^Record Management Services (RMS) attributes include record type and size, among many others.
^MAC/Sensitivity labels are per filesystem. A label per file are not out of the question as a future compatible change but aren't part of any available version of ZFS.
^Solaris "extended attributes" are really full-blown alternate data streams, in both the Solaris UFS and ZFS. ZFS also has "system attributes" used for storing MS-DOS/NTFS compatible attributes for use by CIFS; as well as some attributes ported from FreeBSD
^Context based symlinks were supported in GFS, GFS2 only supports standard symlinks since the bind mount feature of the Linux VFS has made context based symlinks obsolete
^As of Windows Vista, NTFS fully supports soft links. See this Microsoft article on Vista kernel improvements. NTFS 5.0 (Windows 2000) and higher can create junctions, which allow any valid local directory (but not individual files) ("target" of junction) to be mapped to an NTFS version thereof ("source" = location of junction). The source directory must lie on an NTFS 5+ partition, but the target directory can lie on any valid local partition and needn't be NTFS. Junctions are implemented through reparse points, which allow the normal process of filename resolution to be extended in a flexible manner.
^ abNTFS stores everything, even the file data, as meta-data, so its log is closer to block journaling.
^While NTFS itself supports case sensitivity, the Win32 environment subsystem cannot create files whose names differ only by case for compatibility reasons. When a file is opened for writing, if there is any existing file whose name is a case-insensitive match for the new file, the existing file is truncated and opened for writing instead of a new file with a different name being created. Other subsystems like e. g. Services for Unix, that operate directly above the kernel and not on top of Win32 can have case-sensitivity.
^NTFS does not internally support snapshots, but in conjunction with the Volume Shadow Copy Service can maintain persistent block differential volume snapshots.
^Mac OS System 7 introduced the 'alias', analogous to the POSIX symbolic link but with some notable differences. Not only could they cross file systems but they could point to entirely different file servers, and recorded enough information to allow the remote file system to be mounted on demand. It had its own API that application software had to use to gain their benefits-- this is the opposite approach from POSIX which introduced specific APIs to avoid the symbolic link nature of the link. The Finder displayed their file names in an italic font (at least in Roman scripts), but otherwise they behaved identically to their referent.
^Metadata-only journaling was introduced in the Mac OS 10.2.2 HFS Plus driver; journaling is enabled by default on Mac OS 10.3 and later.
^Although often believed to be case sensitive, HFS Plus normally is not. The typical default installation is case-preserving only. From Mac OS 10.3 on the command newfs_hfs -s will create a case-sensitive new file system. HFS Plus version 5 optionally supports case-sensitivity. However, since case-sensitivity is fundamentally different from case-insensitivity, a new signature was required so existing HFS Plus utilities would not see case-sensitivity as a file system error that needed to be corrected. Since the new signature is 'HX', it is often believed this is a new filesystem instead of a simply an upgraded version of HFS Plus. See Apple's File System Comparisons (which hasn't been updated to discuss HFSX) and Technical Note TN1150: HFS Plus Volume Format (which provides a very technical overview of HFS Plus and HFSX).
^Mac OS Tiger (10.4) and late versions of Panther (10.3) provide file change logging (it's a feature of the file system software, not of the volume format, actually). See fslogger.
^HFS+ does not actually encrypt files: to implement FileVault, OS X creates an HFS+ filesystem in a sparse, encrypted disk image that is automatically mounted over the home directory when the user logs in.
^Particular Installable File System drivers and operating systems may not support case sensitivity for JFS. OS/2 does not, and Linux has a mount option for disabling case sensitivity.
^ abZFS is a transactional filesystem using copy-on-write semantics, guaranteeing an always-consistent on-disk state without the use of a traditional journal. However, it does also implement an intent log to provide better performance when synchronous writes are requested.
^ abVariable block size refers to systems which support different block sizes on a per-file basis. (This is similar to extents but a slightly different implementational choice.) The current implementation in UFS2 is read-only.
^Only if formatted with 4kB-sized clusters or smaller
^ abcdOther block:fragment size ratios supported; 8:1 is typical and recommended by most implementations.
^ abcFragments were planned, but never actually implemented on ext2 and ext3.
^e2compr, a set of patches providing block-based compression for ext2, has been available since 1997, but has never been merged into the mainline Linux kernel.
^Each possible size (in sectors) of file tail has a corresponding suballocation block chain in which all the tails of that size are stored. The overhead of managing suballocation block chains is usually less than the amount of block overhead saved by being able to increase the block size but the process is less efficient if there is not much free disk space.
^ abcExt2Fsd is an open source linux ext2/ext3/ext4 file system driver for Windows systems (NT/2K/XP/VISTA, X86/AMD64). Currently does not support extents, a default feature of ext4. [4]
^ abcExt2 IFS for Windows provides kernel level read/write access to Ext2 and Ext3 volumes in Windows NT4, 2000, XP and Vista. Does not support inodes above 128.[5]
^ abcExt2Read is an explorer-like utility to explore ext2/ext3/ext4 file systems. It supports extents, large inodes, and LVM2 volumes.Ext2Read
^ abcFuse-ext2 is a multi OS FUSE module to mount ext2 and ext3 file system devices and/or images with read and write support.[6]
^ abcParagon ExtFS for Mac is a low-level file system driver specially developed to bridge file system incompatibility between Linux and Mac by providing full read/write access to the Ext2, Ext3 and Ext4 file systems under Mac OS X.[7]
^Ext2fsx is the first and old implementation of the Ext2 (Linux) filesystem for Mac OS X.[8]