Comparison of file systems

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The following tables compare general and technical information for a number of file systems.

General information[edit]

File system Creator Year of introduction Original operating system
DECtape DEC 1964 PDP-6 Monitor
Level-D DEC 1968 TOPS-10
George 2 ICT (later ICL) 1968 George 2
V6FS Bell Labs 1972 Version 6 Unix
RT-11 file system DEC 1973 RT-11
Disk Operating System (GEC DOS) GEC 1973 Core Operating System
CP/M file system Gary Kildall 1974 CP/M
GEC DOS filing system extended GEC 1977 OS4000
FAT12 Microsoft 1977 Microsoft Disk BASIC
DOS 3.x Apple Computer 1978 Apple DOS
Pascal Apple Computer 1978 Apple Pascal
CBM DOS Commodore 1978 Microsoft BASIC (for CBM PET)
V7FS Bell Labs 1979 Version 7 Unix
ODS-2 DEC 1979 OpenVMS
DFS Acorn Computers Ltd 1982 Acorn BBC Micro MOS
ADFS Acorn Computers Ltd 1983 Acorn Electron (later Arthur RISC OS)
FFS Kirk McKusick 1983 4.2BSD
ProDOS Apple Computer 1983 ProDOS 8
MFS Apple Computer 1984 Mac OS
Elektronika BK tape format NPO "Scientific centre" (now Sitronics) 1985 Vilnius Basic, BK monitor program
HFS Apple Computer 1985 Mac OS
Amiga OFS[6] Metacomco for Commodore 1985 Amiga OS
High Sierra Ecma International 1985 MS-DOS, Microsoft Windows, Mac OS
NWFS Novell 1985 NetWare 286
FAT16 Microsoft 1987 MS-DOS 3.31
Minix V1 FS Andrew S. Tanenbaum 1987 Minix 1.0
Amiga FFS Commodore 1988 Amiga OS 1.3
HPFS IBM & Microsoft 1988 OS/2
ISO 9660:1988 Ecma International, Microsoft 1988 MS-DOS, Microsoft Windows, Linux, Mac OS X, FreeBSD, and AmigaOS
JFS1 IBM 1990 AIX[1]
VxFS VERITAS 1991 SVR4.0
AdvFS DEC 1993[2] Digital Unix
NTFS Microsoft, Gary Kimura, Tom Miller 1993 Windows NT
LFS Margo Seltzer 1993 Berkeley Sprite
ext2 Rémy Card 1993 Linux, Hurd
UFS1 Kirk McKusick 1994 4.4BSD
XFS SGI 1994 IRIX, Linux, FreeBSD
HFS IBM 1994 MVS/ESA (now z/OS)
Joliet ("CDFS") Microsoft 1995 Microsoft Windows, Linux, Mac OS X, and FreeBSD
UDF ISO/ECMA/OSTA 1995 -
FAT32 Microsoft 1996 Windows 95b[3]
QFS Sun Microsystems 1996 Solaris
GPFS IBM 1996 AIX, Linux
Be File System Be Inc., D. Giampaolo, C. Meurillon 1996 BeOS
Minix V2 FS Andrew S. Tanenbaum 1997 Minix 2.0
HFS Plus Apple Computer 1998 Mac OS 8.1
NSS Novell 1998 NetWare 5
PolyServe File System (PSFS) PolyServe 1998 Windows, Linux
ODS-5 DEC 1998 OpenVMS 7.2
ext3 Dr. Stephen C. Tweedie 1999 Linux
ISO 9660:1999 Ecma International, Microsoft 1999 Microsoft Windows, Linux, Mac OS X, FreeBSD, and AmigaOS
Lustre Sun Microsystems/Cluster File Systems 2002 Linux
JFS IBM 1999 OS/2 Warp Server for e-business
GFS Sistina (Red Hat) 2000 Linux
ReiserFS Namesys 2001 Linux
zFS IBM 2001 z/OS (backported to OS/390)
FATX Microsoft 2002 Xbox
UFS2 Kirk McKusick 2002 FreeBSD 5.0
OCFS Oracle Corporation 2002 Linux
VMFS2 VMware 2002 VMware ESX Server 2.0
Fossil Bell Labs 2003 Plan 9 from Bell Labs 4
Google File System Google 2003 Linux
ZFS Sun Microsystems 2004 Solaris
Reiser4 Namesys 2004 Linux
Non-Volatile File System Palm, Inc. 2004 Palm OS Garnet
Minix V3 FS Andrew S. Tanenbaum 2005 MINIX 3
OCFS2 Oracle Corporation 2005 Linux
NILFS NTT 2005 Linux
VMFS3 VMware 2005 VMware ESX Server 3.0
GFS2 Red Hat 2006 Linux
ext4 various 2006 Linux
exFAT Microsoft 2006 Windows CE 6.0
Btrfs Oracle Corporation 2007 Linux

Limits[edit]

File system Maximum filename length Allowable characters in directory entries[4] Maximum pathname length Maximum file size Maximum volume size[5]
CP/M file system 8.3  ? Initial versions had no subdirectories  ?  ?
IBM SFS 8.8  ?  ? Non-hierarchical[6]  ?
DECtape 6.3 A–Z, 0–9 DTxN:FILNAM.EXT = 15 369,280 bytes (577 * 640) 369,920 bytes (578 * 640)
Elektronika BK tape format 16 bytes No directory hierarchy 64 KiB Not limited. Approx. 800KB (one side) for 90 min cassette
MicroDOS file system 14 bytes 16 MiB 32 MiB
Level-D 6.3 A–Z, 0–9 DEVICE:FILNAM.EXT[PROJCT,PROGRM] = 7 + 10 + 15 = 32; + 5*7 for SFDs = 67 34,359,738,368 words (2**35-1); 206,158,430,208 SIXBIT bytes Approx 12 GB (64 * 178 MB)
RT-11 6.3 A–Z, 0–9, $ 0 (no directory hierarchy) 33,554,432 bytes (65536 * 512) 33,554,432 bytes
V6FS 14 bytes[7] Any byte except NUL and /[8] No limit defined[9] 8 MiB[10] 2 TiB
Disk Operating System (GEC DOS) ? ? ? ? at least 131,072 bytes ?
GEC DOS filing system extended 8 bytes A–Z, 0–9. Period was directory separator ? No limit defined (workaround for OS limit) ? at least 131,072 bytes ?
CBM DOS 16 bytes Any byte except NUL 0 (no directory hierarchy) 16 MiB 16 MiB
V7FS 14 bytes[7] Any byte except NUL and /[8] No limit defined[9] 1 GiB[11] 2 TiB
exFAT 255 UTF-16 characters ? No limit defined 16 EiB ?
FAT12 8.3 (255 UTF-16 characters with LFN)[7] Any Unicode except NUL (with LFN)[7][8] No limit defined[9] 32 MiB 1 MiB to 32 MiB
FAT16 8.3 (255 UTF-16 characters with LFN)[7] Any Unicode except NUL (with LFN)[7][8] No limit defined[9] 2 GiB 16 MiB to 2 GiB
FAT32 8.3 (255 UTF-16 characters with LFN)[7] Any Unicode except NUL (with LFN)[7][8] No limit defined[9] 4 GiB 512 MiB to 8 TiB[12]
FATX 42 bytes[7] ASCII. Unicode not permitted. No limit defined[9] 2 GiB 16 MiB to 2 GiB
Fossil ? ? ? ? ?
MFS 255 bytes Any byte except : No path (flat filesystem) 256 MiB 256 MiB
HFS 31 bytes Any byte except : Unlimited 2 GiB 2 TiB
HPFS 255 bytes Any byte except NUL[13] No limit defined[9] 2 GiB 2 TiB[14]
NTFS 255 characters Any Unicode except NUL, / 32,767 Unicode characters with each path component (directory or filename) up to 255 characters long[9] 16 EiB[15] 16 EiB[15]
HFS Plus 255 UTF-16 characters[16] Any valid Unicode[17][8] Unlimited slightly less than 8 EiB slightly less than 8 EiB[18]
FFS 255 bytes Any byte except NUL[8] No limit defined[9] 4 GiB 256 TiB
UFS1 255 bytes Any byte except NUL[8] No limit defined[9] 4 GiB to 256 TiB 256 TiB
UFS2 255 bytes Any byte except NUL[8] No limit defined[9] 512 GiB to 32 PiB 1 YiB
ext2 255 bytes Any byte except NUL[8] No limit defined[9] 16 GiB to 2 TiB[5] 2 TiB to 32 TiB
ext3 255 bytes Any byte except NUL[8] No limit defined[9] 16 GiB to 2 TiB[5] 2 TiB to 32 TiB
ext4 255 bytes Any byte except NUL[8] No limit defined[9] 16 GiB to 16 TiB[5][19] 1 EiB
Lustre 255 bytes Any byte except NUL[8] No limit defined[9] 320 TiB on ext4 (16 TiB tested) 220 EiB on ext4 (2 PiB tested)
GPFS 255 UTF-8 codepoints Any byte except NUL[8] No limit defined[9] No limit found 299 bytes (2 PiB tested)
GFS 255 Any byte except NUL[8] No limit defined[9] 2 TB to 8 EB[20] 2 TB to 8 EB[20]
NILFS 255 bytes Any byte except NUL[8] No limit defined[9] 8 EiB 8 EiB
ReiserFS 4,032 bytes/255 characters Any byte except NUL[8] No limit defined[9] 8 TiB[21] (v3.6), 4 GiB (v3.5) 16 TiB
Reiser4 3,976 bytes Any byte except / and NUL No limit defined[9] 8 TiB on x86 ?
OCFS 255 bytes Any byte except NUL[8] No limit defined[9] 8 TiB 8 TiB
OCFS2 255 bytes Any byte except NUL[8] No limit defined[9] 4 PiB 4 PiB
XFS 255 bytes[22] Any byte except NUL[8] No limit defined[9] 8 EiB[23] 8 EiB[23]
JFS1 255 bytes Any byte except NUL[8] No limit defined[9] 8 EiB 512 TiB to 4 PiB
JFS 255 bytes Any Unicode except NUL No limit defined[9] 4 PiB 32 PiB
QFS 255 bytes Any byte except NUL[8] No limit defined[9] 16 EiB[24] 4 PiB[24]
BFS 255 bytes Any byte except NUL[8] No limit defined[9] 12,288 bytes to 260 GiB[25] 256 PiB to 2 EiB
AdvFS 255 characters Any byte except NUL[8] No limit defined[9] 16 TiB 16 TiB
NSS 256 characters Depends on namespace used[26] Only limited by client 8 TiB 8 TiB
NWFS 80 bytes[27] Depends on namespace used[26] No limit defined[9] 4 GiB 1 TiB
ODS-5 236 bytes[28] ? 4,096 bytes[29] 1 TiB 1 TiB
VxFS 255 bytes Any byte except NUL[8] No limit defined[9] 16 EiB ?
UDF 255 bytes Any Unicode except NUL 1,023 bytes[30] 16 EiB ?
ZFS 255 bytes Any Unicode except NUL No limit defined[9] 16 EiB 218 EiB (278 bytes)
Btrfs 255 bytes Any byte except '/' and NUL No limit defined 16 EiB 16 EiB
Minix V1 FS 14 or 30 bytes, set at filesystem creation time Any byte except NUL[8] No limit defined[9] 1 GiB 1 GiB
Minix V2 FS 14 or 30 bytes, set at filesystem creation time Any byte except NUL[8] No limit defined[9] 1 GiB 1 GiB
Minix V3 FS 60 bytes Any byte except NUL[8] No limit defined[9] 4 GiB 4 GiB
VMFS2 128 Any byte except NUL and /[8] 2,048 4 TiB[31] 64 TiB
VMFS3 128 Any byte except NUL and /[8] 2,048 2 TiB[31] 64 TiB
ISO 9660:1988 Level 1: 8.3,
Level 2 & 3: ~ 180
Depends on Level[32] ~ 180 bytes? 4 GiB (Level 1 & 2) to 8 TiB (Level 3)[33] 8 TiB[34]
Joliet ("CDFS") 64 Unicode characters All UCS-2 code except *, /, \, :, ;, and ?[35]  ? same as ISO 9660:1988 same as ISO 9660:1988
ISO 9660:1999  ?  ?  ?  ?  ?
High Sierra  ?  ?  ?  ?  ?
File system Maximum filename length Allowable characters in directory entries[4] Maximum pathname length Maximum file size Maximum volume size[5]

Metadata[edit]

File system Stores file owner POSIX file permissions Creation timestamps Last access/ read timestamps Last modification of content This copy created Last metadata change timestamps Last archive timestamps Access control lists Security/ MAC labels Extended attributes/ Alternate data streams/ forks Checksum/ ECC
CP/M file system No No Yes[36] No No No No No No No
DECtape No No Yes No No No No No No No
Elektronika BK tape format No No No No No No No No No Yes
Level-D Yes Yes Yes Yes Yes Yes Yes No No No
RT-11 No No Yes No No No No No No No
V6FS Yes Yes No Yes Yes No No No No No
V7FS Yes Yes No Yes Yes No No No No No
FAT12 No No Yes Yes No[37] No No No No[38] No
FAT16 No No Yes Yes Yes No No[37] No No No No[38] No
FAT32 No No Yes Yes Yes No No[37] No No No No No
HPFS Yes[39] No Yes Yes No No No ? Yes No
NTFS Yes Yes[40] Yes Yes Yes No Yes Yes[41] Yes No
HFS No No Yes No No Yes No No Yes No
HFS Plus Yes Yes Yes Yes Yes Yes Yes ? Yes No
FFS Yes Yes No Yes Yes No No No No No
UFS1 Yes Yes No Yes Yes No Yes[42] Yes[42] No[43] No
UFS2 Yes Yes Yes Yes Yes No Yes[42] Yes[42] Yes No
LFS Yes Yes No Yes Yes No No No No No
ext2 Yes Yes No Yes Yes No Yes[44] Yes[44] Yes No
ext3 Yes Yes No Yes Yes No Yes No Yes[44] Yes[44] Yes No
ext4 Yes Yes Yes Yes Yes No Yes[44] Yes[44] Yes No
Lustre Yes Yes No Yes Yes No Yes Yes Yes No
GPFS Yes Yes Yes Yes Yes No Yes Yes Yes Yes
GFS Yes Yes No Yes Yes No Yes[44] Yes[44] Yes No
NILFS Yes Yes Yes No Yes No No No No Yes
ReiserFS Yes Yes No Yes Yes No Yes No Yes[44] Yes[44] Yes No
Reiser4 Yes Yes No Yes Yes No No No No No
OCFS No Yes No No Yes Yes No No No No
OCFS2 Yes Yes No Yes Yes No No No No No
XFS Yes Yes No Yes Yes No Yes Yes[44] Yes No
JFS Yes Yes Yes Yes Yes No Yes Yes Yes No
QFS Yes Yes Yes Yes Yes Yes Yes No Yes No
BFS Yes Yes Yes No No No No No Yes No
AdvFS Yes Yes No Yes Yes No Yes No Yes No
NSS Yes Yes Yes[45] Yes[45] Yes Yes[45] Yes ? Yes[46][47] No
NWFS Yes ? Yes[45] Yes[45] Yes Yes[45] Yes ? Yes[46][47] No
ODS-5 Yes Yes Yes ? ? Yes Yes ? Yes[48] No
VxFS Yes Yes Yes Yes Yes No Yes ? Yes[44] No
UDF Yes Yes Yes Yes Yes Yes Yes No Yes No
Fossil Yes Yes[49] No Yes Yes No No No No No
ZFS Yes Yes Yes Yes Yes Yes Yes No[50] Yes[51] Yes
VMFS2 Yes Yes No Yes Yes No No No No No
VMFS3 Yes Yes No Yes Yes No No No No No
ISO 9660:1988 No No Yes No No No No No No No
Joliet ("CDFS") No No Yes No No No No No No No
ISO 9660:1999 No No Yes No No No No No No No
High Sierra No No Yes No No No No No No No
File system Stores file owner POSIX file permissions Creation timestamps Last access/read timestamps Last metadata change timestamps Last archive timestamps Access control lists Security/ MAC labels Extended attributes/ Alternate data streams/ forks Checksum/ ECC

Features[edit]

File system Hard links Symbolic links Block journaling Metadata-only journaling Case-sensitive Case-preserving File Change Log Internal snapshotting / branching XIP Filesystem-level encryption
DECtape No No No No No No No No No No
Level-D No No No No No No No No No No
RT-11 No No No No No No No No No No
V6FS Yes No No No Yes Yes No No No No
V7FS Yes No[52] No No Yes Yes No No No No
FAT12 No No No No No No No No No No
FAT16 No No No No No Partial No No No No
FAT32 No No No No No Partial No No No No
GFS Yes Yes[53] Yes Yes[54] Yes Yes No No No No
HPFS No No No No No Yes No ? No No
NTFS Yes Yes[55] No[56] Yes[56] Yes[57] Yes Yes Partial[58] ? Yes
HFS Plus Partial Yes No Yes[59] Partial[60] Yes Yes[61] No No No[62]
FFS Yes Yes No No Yes Yes No No No No
UFS1 Yes Yes No No Yes Yes No No No No
UFS2 Yes Yes No No[63] Yes Yes No Yes ? No
LFS Yes Yes Yes[64] No Yes Yes No Yes No No
ext2 Yes Yes No No Yes Yes No No Yes[65] No
ext3 Yes Yes Yes[66] Yes Yes Yes No No Yes No
ext4 Yes Yes Yes[66] Yes Yes Yes No No Yes No
Lustre Yes Yes Yes[66] Yes Yes Yes No No No No
NILFS Yes Yes Yes[64] No Yes Yes No Yes No No
ReiserFS Yes Yes Yes[67] Yes Yes Yes No No ? No
Reiser4 Yes Yes Yes No Yes Yes No ? ? Yes[68]
OCFS No Yes No No Yes Yes No No No No
OCFS2 Yes Yes Yes Yes Yes Yes No No No No
XFS Yes Yes No Yes Yes[69] Yes Yes No ? No
JFS Yes Yes No Yes Yes[70] Yes No ? ? No
QFS Yes Yes No Yes Yes Yes No No No No
Be File System Yes Yes No Yes Yes Yes ? ? No No
NSS Yes Yes ? Yes Yes[71] Yes[71] Yes[72] Yes No Yes
NWFS Yes[73] Yes[73] No No Yes[71] Yes[71] Yes[72] ? No No
ODS-2 Yes Yes[74] No Yes No No Yes Yes No No
ODS-5 Yes Yes[74] No Yes No Yes Yes Yes ? No
UDF Yes Yes Yes[64] Yes[64] Yes Yes No No Yes No
VxFS Yes Yes Yes No Yes Yes Yes Yes[75] ? No
Fossil No No No No Yes Yes Yes Yes No No
ZFS Yes Yes Yes[76] No[76] Yes Yes No Yes No No
VMFS2 Yes Yes No Yes Yes Yes No No No No
VMFS3 Yes Yes No Yes Yes Yes No No No No
File system Hard links Symbolic links Block journaling Metadata-only journaling Case-sensitive Case-preserving File Change Log Internal snapshotting / branching XIP Filesystem-level encryption

Allocation and layout policies[edit]

File system Tail packing Transparent compression Block suballocation Allocate-on-flush Extents Variable file block size[77] Sparse files
DECtape No No No No No No No
Level-D No No Yes No Yes No No
V6FS No No No No No No Yes
V7FS No No No No No No Yes
FAT12 No No[78] No No No No No
FAT16 No No[78] No No No No No
FAT32 No No No No No No No
GFS Partial[79] No No No No No Yes
HPFS No No No No Yes No No
NTFS No Yes Partial No Yes No Yes
HFS Plus No No No No Yes No No
FFS No No 8:1[80] No No No ?
UFS1 No No 8:1[80] No No No Yes
UFS2 No No 8:1[80] No No Yes Yes
LFS No No 8:1[80] No No No Yes
ext2 No No[81] No[82] No No No Yes
ext3 No No No[82] No No No Yes
ext4 No No No[82] Yes Yes No Yes
Lustre No No No Yes Yes No Yes
NILFS No No No Yes No No Yes
ReiserFS Yes No Yes[83] No No No Yes
Reiser4 Yes Yes[68] Yes[83] Yes Yes[84] No Yes
OCFS No No No No Yes No ?
OCFS2 No No No No Yes No Yes
XFS No No No Yes Yes No Yes
JFS No only in JFS1 on AIX[85] Yes No Yes No Yes
QFS No No Yes No No No ?
BFS No No No No Yes No ?
NSS No Yes No No Yes No ?
NWFS No Yes Yes[86] No No No ?
ODS-5 No No No No Yes No ?
VxFS No No ? No Yes No Yes
UDF No No No ?[87] Yes No No
Fossil No Yes No No No No ?
ZFS Partial[88] Yes ? Yes No Yes Yes
VMFS2 No No Yes No No No Yes
VMFS3 No No Yes No No No Yes
File system Tail packing Transparent compression Block suballocation Allocate-on-flush Extents Variable file block size[77] Sparse files

OS support[edit]

File system Windows 9x Windows NT Linux Mac OS Mac OS X FreeBSD OS/2 BeOS Minix Solaris z/OS
DECtape ? ? ? ? ? No ? ? ? ? ?
Level-D ? ? ? ? ? No ? ? ? ? ?
RT-11 ? ? ? ? ? No ? ? ? ? ?
V6FS ? ? ? ? ? No ? ? ? ? ?
V7FS ? ? Yes ? ? No ? ? ? ? ?
FAT12 Yes Yes Yes ? Yes Yes Yes Yes ? Yes ?
FAT16 Yes Yes Yes ? Yes Yes Yes Yes ? Yes ?
FAT32 Yes Yes from Windows 2000 Yes ? Yes Yes Yes Yes ? Yes ?
GFS ? ? Yes ? ? No ? ? ? ? ?
HPFS ? ? Yes ? ? Yes Yes ? ? ? ?
NTFS No Yes Yes with ntfs-3g Yes with Paragon NTFS and ntfs-3g Yes with ntfs-3g Yes with ntfs-3g ? Yes with ntfs-3g ? ? ?
Apple HFS ? ? Yes Yes Yes No ? Yes ? ? No
Apple HFS Plus ? ? Partial - writing support only to unjournalled FS Yes from Mac OS 8.1 Yes No ? Template:Yes with addon ? ? No
FFS ? ? ? ? Yes Yes ? ? ? ? ?
UFS1 ? ? Partial - read only ? Yes Yes ? ? ? ? ?
UFS2 ? ? Partial - read only ? Yes Yes ? ? ? ? ?
LFS ? ? ? ? ? No ? ? ? ? ?
ext2 ? Yes with Ext2 IFS[89] or ext2fsd[90] Yes Yes with ext2fsx Yes with ext2fsx Yes ? Yes ? ? ?
ext3 ? Yes with Ext2 IFS[89] or ext2fsd[90] Yes ? Partial with ext2fsx (journal not updated on writing) ? ? Template:Yes, with addon ? Yes ?
ext4 ? ? Yes ? ? No ? Template:Yes, with addon ? ? ?
Lustre ? ? Yes[91] ? ? No ? ? ? Yes ?
NILFS ? ? Yes as an external kernel module ? ? No ? ? ? ? ?
ReiserFS ? ? Yes ? ? Yes Read Only ? Template:Yes, with addon ? ? ?
Reiser4 ? ? Yes with a kernel patch ? ? No ? ? ? ? ?
OCFS ? ? Yes ? ? No ? ? ? ? ?
OCFS2 ? ? Yes ? ? No ? ? ? ? ?
XFS ? ? Yes ? ? Partial ? Template:Yes, with addon (read only) ? ? ?
JFS ? ? Yes ? ? No Yes ? ? ? ?
QFS ? ? ? ? ? No ? ? ? Yes ?
Be File System ? ? Partial - read-only ? ? No ? Yes ? ? ?
NSS ? ? Yes via EVMS[92] ? ? No ? ? ? ? ?
NWFS ? ? ? ? ? Yes ? ? ? ? ?
ODS-2 ? ? ? ? ? No ? ? ? ? ?
ODS-5 ? ? ? ? ? No ? ? ? ? ?
UDF ? Yes[citation needed] Yes ? Yes Yes ? ? ? Yes ?
VxFS ? ? Yes ? ? No ? ? ? Yes ?
Fossil No No Yes[93] No Yes[93] Yes[93] No No No Yes[93] ?
Sun ZFS ? ? Yes with FUSE[94] ? Yes with Read/Write Developer Preview[95] Yes ? ? ? Yes ?
VMFS2 ? ? ? ? ? No ? ? ? ? ?
VMFS3 ? ? ? ? ? No ? ? ? ? ?
IBM HFS No No No No No No No No No No Yes
IBM zFS No No No No No No No No No No Yes
File system Windows 9x Windows NT Linux Mac OS Mac OS X FreeBSD OS/2 BeOS Minix Solaris z/OS

See also[edit]

Notes[edit]

  1. ^ IBM introduced JFS with the initial release of AIX Version 3.1 in 1990. This file system now called JFS1. The new JFS, on which the Linux port was based, was first shipped in OS/2 Warp Server for e-Business in 1999. The same sourcebase was also used for release JFS2 on AIX 5L.
  2. ^ Polycenter File System - - HELP
  3. ^ 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.
  4. ^ a b These 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. Unices and Linux disallow the characters / and NUL in file and directory names across all filesystems.
  5. ^ a b c d e For 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 KiB 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 KiB).
  6. ^ SFS file system
  7. ^ a b c d e f g h i Depends on whether the FAT12, FAT16, and FAT32 implementation has support for LFNs. Where it does not, as in OS/2, MS-DOS, Windows 95, Windows 98 in DOS-only mode and the Linux "msdos" driver, file names are limited to 8.3 format of 8-bit characters (space padded in both the basename and extension parts) and may not contain NUL (end-of-directory marker) or character 5 (replacement for character 229 which itself is used as deleted-file marker). Short names also do not normally contain lowercase letters. Also note that a few special names (CON, NUL, LPT1) should be avoided, as some operating systems (notably DOS and windows) effectively reserve them.
  8. ^ a b c d e f g h i j k l m n o p q r s t u v w x y z aa ab ac ad In these filesystems the directory entries named "." and ".." have special status. Directory entries with these names are not prohibited, and indeed exist as normal directory entries in the on-disk data structures. However, they are mandatory directory entries, with mandatory values, that are automatically created in each directory when it is created; and directories without them are considered corrupt.
  9. ^ a b c d e f g h i j k l m n o p q r s t u v w x y z aa ab ac ad ae af ag ah The on-disk structures have no inherent limit. Particular Installable File System drivers and operating systems may impose limits of their own, however. MS-DOS does not support full pathnames longer than 260 bytes for FAT12 and FAT16. Windows NT does not support full pathnames longer than 32,767 bytes for NTFS. Linux has a pathname limit of 4,096.
  10. ^ The actual maximum was 8,847,360 bytes, with 7 singly-indirect blocks and 1 doubly-indirect block; PWB/UNIX 1.0's variant had 8 singly-indirect blocks, making the maximum 524,288 bytes or half a MiB.
  11. ^ The actual maximum was 1,082,201,088 bytes, with 10 direct blocks, 1 singly-indirect block, 1 doubly-indirect block, and 1 triply-indirect block. The 4.0BSD and 4.1BSD versions, and the System V version, used 1,024-byte blocks rather than 512-byte blocks, making the maximum 4,311,812,608 bytes or approximately 4 GiB.
  12. ^ While FAT32 partitions this large work fine once created, some software won't allow creation of FAT32 partitions larger than 32 GiB. This includes, notoriously, the Windows XP installation program and the Disk Management console in Windows 2000, XP, 2003 and Vista. Use FDISK from a Windows ME Emergency Boot Disk to avoid. [1]
  13. ^ The "." and ".." directory entries in HPFS that are seen by applications programs are a partial fiction created by the Installable File System drivers. The on-disk data structure for a directory does not contain entries by those names, but instead contains a special "start" entry. Whilst on-disk directory entries by those names are not physically prohibited, they cannot be created in normal operation, and a directory containing such entries is corrupt.
  14. ^ This is the limit of the on-disk structures. The HPFS Installable File System driver for OS/2 uses the top 5 bits of the volume sector number for its own use, limiting the volume size that it can handle to 64 GiB.
  15. ^ a b This is the limit of the on-disk structures. The NTFS driver for Windows NT limits the volume size that it can handle to 256 TiB and the file size to 16 TiB respectively.
  16. ^ The Mac OS provides two sets of functions to retrieve file names from an HFS Plus volume, one of them returning the full Unicode names, the other shortened names fitting in the older 31 byte limit to accommodate older applications.
  17. ^ HFS Plus mandates support for an escape sequence to allow arbitrary Unicode. Users of older software might see the escape sequences instead of the desired characters.
  18. ^ See http://docs.info.apple.com/article.html?artnum=25557 and http://docs.info.apple.com/article.html?artnum=24601.
  19. ^ http://fedoraproject.org/wiki/Interviews/EricSandeen
  20. ^ a b Depends on kernel version and arch. For 2.4 kernels the max is 2 TiB. For 32-bit 2.6 kernels it is 16 TiB. For 64-bit 2.6 kernels it is 8 EiB.
  21. ^ ReiserFS has a theoretical maximum file size of 1 EiB, but "page cache limits this to 8 Ti on architectures with 32 bit int"[2]
  22. ^ Note that the filename can be much longer XFS#Extended_attributes
  23. ^ a b XFS has a limitation under Linux 2.4 of 64 TiB file size, but Linux 2.4 only supports a maximum block size of 2 TiB. This limitation is not present under IRIX.
  24. ^ a b QFS 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.
  25. ^ Varies wildly according to block size and fragmentation of block allocation groups.
  26. ^ a b NSS allows files to have multiple names, in separate namespaces.
  27. ^ Some namespaces had lower name length limits. "LONG" had an 80-byte limit, "NWFS" 80 bytes, "NFS" 40 bytes and "DOS" imposed 8.3 filename.
  28. ^ Maximum combined filename/filetype length is 236 bytes; each component has an individual maximum length of 255 bytes.
  29. ^ Maximum pathname length is 4,096 bytes, but quoted limits on individual components add up to 1,664 bytes.
  30. ^ This restriction might be lifted in newer versions.
  31. ^ a b Maximum file size on a VMFS volume depends on the block size for that VMFS volume. The figures here are obtained by using the maximum block size.
  32. ^ ISO_9660#Restrictions
  33. ^ Through the use of multi-extents, a file can consist of multiple segments, each up to 4 GiB in size. See ISO_9660#The_2_GiB_.28or_4_GiB_depending_on_implementation.29_file_size_limit
  34. ^ Assuming the typical 2048 Byte sector size. The volume size is specified as a 32 bit value identifying the number of sectors on the volume.
  35. ^ Joliet Specification
  36. ^ Implemented in later versions as an extension
  37. ^ a b c Some FAT implementations, such as in Linux, show file modification timestamp (mtime) in the metadata change timestamp (ctime) field. This timestamp is however, not updated on file metadata change.
  38. ^ a b Particular Installable File System drivers and operating systems may not support extended attributes on FAT12 and FAT16. The OS/2 and Windows NT filesystem drivers for FAT12 and FAT16 support extended attributes (using a "EA DATA. SF" pseudo-file to reserve the clusters allocated to them). Other filesystem drivers for other operating systems do not.
  39. ^ The f-node contains a field for a user identifier. This is not used except by OS/2 Warp Server, however.
  40. ^ 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.
  41. ^ As of Vista, NTFS has support for Mandatory Labels, which are used to enforce Mandatory Integrity Control. See [3]
  42. ^ a b c d Access-control lists and MAC labels are layered on top of extended attributes.
  43. ^ Some operating systems implemented extended attributes as a layer over UFS1 with a parallel backing file (e.g., FreeBSD 4.x).
  44. ^ a b c d e f g h i j k l Some 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.
  45. ^ a b c d e f The local time, timezone/UTC offset, and date are derived from the time settings of the reference/single timesync source in the NDS tree.
  46. ^ a b Novell calls this feature "multiple data streams". Published specifications say that NWFS allows for 16 attributes and 10 data streams, and NSS allows for unlimited quantities of both.
  47. ^ a b Some file and directory metadata is stored on the NetWare server irrespective of whether Directory Services is installed or not, like date/time of creation, file size, purge status, etc; and some file and directory metadata is stored in NDS/eDirectory, like file/object permissions, ownership, etc.
  48. ^ Record Management Services (RMS) attributes include record type and size, among many others.
  49. ^ File permission in 9P are a variation of the traditional Unix permissions with some minor changes, eg. the suid bit is replaced by a new 'exclusive access' bit.
  50. ^ MAC/Sensitivity labels in the file system are not out of the question as a future compatible change but aren't part of any available version of ZFS.
  51. ^ Solaris "extended attributes" are really full-blown alternate data streams, in both the Solaris UFS and ZFS.
  52. ^ System V Release 4, and some other Unix systems, retrofitted symbolic links to their versions of the Version 7 Unix file system, although the original version didn't support them.
  53. ^ 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
  54. ^ Optional journaling of data
  55. ^ As of Windows Vista, NTFS fully supports soft links. See this Microsoft article on Vista kernel improvements. NTFS 3.0 (Windows 2000) and higher can create junctions, which allow entire directories (but not individual files) to be mapped to elsewhere in the directory tree of the same partition (file system). These are implemented through reparse points, which allow the normal process of filename resolution to be extended in a flexible manner.
  56. ^ a b NTFS stores everything, even the file data, as meta-data, so its log is closer to block journaling.
  57. ^ 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.
  58. ^ NTFS does not internally support snapshots, but in conjunction with the Volume Shadow Copy Service can maintain persistent block differential volume snapshots.
  59. ^ 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.
  60. ^ 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).
  61. ^ 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.
  62. ^ 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.
  63. ^ "Soft dependencies" (softdep) in NetBSD, called "soft updates" in FreeBSD provide meta-data consistency at all times without double writes (journaling).
  64. ^ a b c d UDF, LFS, and NILFS are log-structured file systems and behave as if the entire file system were a journal.
  65. ^ Linux kernel versions 2.6.12 and newer.
  66. ^ a b c Off by default.
  67. ^ Full block journaling for ReiserFS was added to Linux 2.6.8.
  68. ^ a b Reiser4 supports transparent compression and encryption with the cryptcompress plugin which is the default file handler in version 4.1.
  69. ^ Optionally no on IRIX.
  70. ^ 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.
  71. ^ a b c d Case-sensitivity/Preservation depends on client. Windows, DOS, and OS/2 clients don't see/keep case differences, whereas clients accessing via NFS or AFP may.
  72. ^ a b The file change logs, last entry change timestamps, and other filesystem metadata, are all part of the extensive suite of auditing capabilities built into NDS/eDirectory called NSure Audit. (Filesystem Events tracked by NSure)
  73. ^ a b Available only in the "NFS" namespace.
  74. ^ a b These are referred to as "aliases".
  75. ^ VxFS provides an optional feature called "Storage Checkpoints" which allows for advanced file system snapshots.
  76. ^ a b ZFS 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.
  77. ^ a b Variable 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.
  78. ^ a b DoubleSpace in DOS 6, and DriveSpace in Windows 95 and Windows 98 were data compression schemes for FAT, but are no longer supported by Microsoft.
  79. ^ Only for "stuffed" inodes
  80. ^ a b c d Other block:fragment size ratios supported; 8:1 is typical and recommended by most implementations.
  81. ^ 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.
  82. ^ a b c Fragments were planned, but never actually implemented on ext2 and ext3.
  83. ^ a b Tail packing is technically a special case of block suballocation where the suballocation unit size is always 1 byte.
  84. ^ In "extents" mode.
  85. ^ "AIX documentation: JFS data compression". IBM. 
  86. ^ 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.
  87. ^ Depends on UDF implementation.
  88. ^ When enabled, ZFS's logical-block based compression behaves much like tail-packing for the last block of a file.
  89. ^ a b Ext2 IFS for Windows provides kernel level read/write access to Ext2 and Ext3 volumes in Windows NT4, 2000, XP and Vista.[4]
  90. ^ a b Ext2Fsd is an open source linux ext2/ext3 file system driver for Windows systems (NT/2K/XP/VISTA, X86/AMD64).[5]
  91. ^ http://wiki.lustre.org/index.php?title=Main_Page
  92. ^ Supported using only EVMS; not currently supported using LVM
  93. ^ a b c d Provided in Plan 9 from User Space
  94. ^ ZFS on FUSE
  95. ^ Apple Seeds ZFS Read/Write Developer Preview 1.1 for Leopard - Mac Rumors

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