Filesystems HOWTO
Martin Hinner <
[email protected]>
Version 0.7.4, 17 March 2000
This small HOWTO is about filesystems and accessing filesystems. It is
not Linux- or Unix-related document as you probably expect. You can
find there also a lot of interesting information about non-Unix
(file)systems, but Unix is my primary interest :-)
______________________________________________________________________
Table of Contents
1. Introduction
1.1 Copyright
1.2 Filesystems mailing-list
1.2.1 Linux kernel filesystems mailing-list
1.2.2 FreeBSD filesystems mailing-list
1.3 Filesystems collection at metalab.unc.edu
1.4 Credits
1.5 Filesystems accessibility map
1.6 Introduction to contiguous allocation filesystems
1.7 Introduction to linked-list allocation filesystems
1.8 Introduction to FAT-based filesystems
1.9 Introduction to Inode filesystems
1.10 Introduction to extent filesystems
1.11 Introduction to filesystems using balanced trees
1.12 Introduction to logging/journaling filesystems
1.13 Other filesystem features
1.13.1 Quota
1.13.2 Snapshot
1.13.3 ACLs
2. Volumes
2.1 PC Partitions
2.1.1 GNU parted
2.1.2 Repairing corrupted partition table
2.1.2.1 Fixdisktable
2.1.2.2 gpart
2.1.2.3 rescuept
2.1.2.4 findsuper
2.2 Other partitions
2.2.1 ADFS partitions
2.2.2 Amiga partitions
2.2.3 ATARI partitions
2.2.4 Macintosh partitions
2.2.5 OSF partitions
2.2.6 Sun partitions
2.2.7 Ultrix partitions
2.3 Unix disklabels
2.3.1 BSD disklabel
2.3.2 UnixWare disklabel
2.3.3 SCO OpenServer disklabel
2.3.4 Sun Solaris disklabel
2.4 Windows NT volumes
2.4.1 Repairing "fault tolerant" NTFS disks using FTEdit
2.5 MD - Multiple Devices driver for Linux
2.6 LVM - Logical Volume Manager (HP-UX LVM?)
2.7 VxVM - Veritas Volume Manager
2.8 IBM OS/2 LVM
2.9 StackVM
2.10 Novell NetWare volumes
3. DOS FAT 12/16/32, VFAT
3.1 VFAT: Long filenames
3.2 UMSDOS: Linux LFN/attributes on FAT filesystem
3.3 OS/2 Extended Attributes on FAT filesystems
3.4 Star LFN
3.5 Accessing VFAT from OS/2 (VFAT-OS2)
3.6 Accessing VFAT from DOS (LFNDOS driver)
3.7 Accessing VFAT from DOS (Free LFNDOS driver)
3.8 Accessing VFAT from DOS (Odi's LFN tools)
3.9 Accessing FAT32 from OS/2 (FAT32.IFS)
3.10 Accessing FAT32 from Windows NT 4.0
3.11 Accessing FAT32 from Windows NT 4.0
3.12 Accessing Stac/Dblspaced/Drvspaced drives from Linux (DMSDOS)
3.13 Accessing Dblspaced/Drvspaced drives from Linux (thsfs)
3.14 Fsresize - FAT16/32 resizer
3.15 FIPS - FAT16 resizer
4. High Performance FileSystem (HPFS)
4.1 Accessing HPFS from DOS (iHPFS)
4.2 Accessing HPFS from DOS (hpfsdos)
4.3 Accessing HPFS from DOS (hpfsa)
4.4 Accessing HPFS from DOS (amos)
4.5 Accessing HPFS from Linux
4.6 Accessing HPFS from FreeBSD
4.7 Accessing HPFS from Windows NT 3.5
4.8 Accessing HPFS from Windows NT 4
5. New Technology FileSystem (NTFS)
5.1 Accessing NTFS from DOS (NTFSDOS.EXE)
5.2 Accessing NTFS from DOS (ntpwd)
5.3 Accessing NTFS from OS/2
5.4 Accessing NTFS from Linux
5.5 Accessing NTFS from FreeBSD and NetBSD
5.6 Accessing NTFS from BeOS
5.7 Accessing NTFS from BeOS (another)
5.8 Repairing NTFS using NTFSDOS Tools
5.9 Repairing NTFS using NTRecover
6. Extended filesystems (Ext, Ext2, Ext3)
6.1 Extended filesystem (ExtFS)
6.2 Second Extended Filesystem (Ext2 FS)
6.2.1 Motivations
6.2.2 ``Standard'' Ext2fs features
6.2.3 ``Advanced'' Ext2fs features
6.2.4 Physical Structure
6.2.5 Performance optimizations
6.3 Third Extended Filesystem (Ext3 FS)
6.4 E2compr - Ext2fs transparent compression
6.5 Accessing Ext2 from DOS (Ext2 tools)
6.6 Accessing Ext2 from DOS, Windows 9x/NT and other Unixes (LTools)
6.7 Accessing Ext2 from OS/2
6.8 Accessing Ext2 from Windows 95/98 (FSDEXT2)
6.9 Accessing Ext2 from Windows 95 (Explore2fs)
6.10 Accessing Ext2 from Windows NT (ext2fsnt)
6.11 Accessing Ext2 from BeOS
6.12 Accessing Ext2 from MacOS (MountX)
6.13 Accessing Ext2 from MiNT
6.14 Ext2fs defrag
6.15 Ext2fs resize
6.16 Ext2end
6.17 Repairing/analyzing/creating Ext2 using E2fsprogs
6.18 Ext2 filesystem editor - Ext2ed
6.19 Linux filesystem editor - lde
6.20 Ext2 undelete utilities
7. Macintosh Hierarchical Filesystem - HFS
7.1 Accessing HFS from Linux
7.2 Accessing HFS from OS/2 (HFS/2)
7.3 Accessing HFS from Windows 95/98/NT (HFV Explorer)
7.4 Accessing HFS from DOS (MAC-ETTE)
7.5 HFS utils
7.6 MacFS: A Portable Macintosh File System Library
8. ISO 9660 - CD-ROM filesystem
8.1 RockRidge extensions
8.2 Joliet extensions
8.3 Hybrid CD-ROMs
8.4 Physical formats
8.4.1 CD-DA - Audio CDs
8.4.2 Data CDs
8.4.3 Recordable CDs
8.4.3.1 CD-MO - Magneto-optical
8.4.3.2 CD-WO - Write-once
8.4.3.3 CD-RW - Rewritable CDs
8.4.4 CD Extra - eXtended Architecture
8.4.4.1 MODE-1
8.4.4.2 MODE-2
8.4.4.2.1 FORM-1
8.4.4.2.2 FORM-2
8.4.5 Video CD
8.5 Accessing Joliet from Linux
8.6 Accessing Joliet from BeOS
8.7 Accessing Joliet from OS/2
8.8 Accessing Audio CD as filesystem from BeOS
8.9 Creating Hybrid CD-ROMs (mkhybrid)
9. Other filesystems
9.1 ADFS - Acorn Disc File System
9.2 AFFS - Amiga fast filesystem
9.3 BeFS - BeOS filesystem
9.4 BFS - UnixWare Boot Filesystem
9.5 CrosStor filesystem
9.6 DTFS - Desktop filesystem
9.7 EFS - Enhanced filesystem (Linux)
9.8 EFS - Extent filesystem (IRIX)
9.8.1 EFS and UFS library, libfs
9.9 FFS - BSD Fast filesystem
9.10 GPFS - General Parallel Filesystem
9.11 HFS - HP-UX Hi performance filesystem
9.12 HTFS - High throughput filesystem
9.13 JFS - Journaled filesystem (HP-UX, AIX, OS/2 5)
9.14 LFS - Linux log structured filesystem
9.15 MFS - Macintosh filesystem
9.16 Minix filesystem
9.17 NWFS - Novell NetWare filesystem
9.17.1 NetWare filesystem / 286
9.17.2 NetWare filesystem / 386
9.17.3 Accessing NWFS-386 from Linux
9.18 NSS - Novell Storage Services
9.19 ODS - On Disk Structure filesystem
9.20 QNX filesystem
9.21 Reiser filesystem
9.22 RFS (CD-ROM Filesystem)
9.23 RomFS - Rom filesystem
9.24 SFS - Secure filesystem
9.25 Spiralog filesystem (OpenVMS)
9.26 System V and derived filesystems
9.26.1 AFS - Acer Fast Filesystem
9.26.2 EAFS - Extended Acer Fast Filesystem
9.26.3 Coherent filesystem
9.26.4 S5
9.26.5 S51K - SystemV 1K
9.26.6 Version 7 filesystem
9.26.7 Xenix filesystem
9.27 Text - (Philips' CD-ROM Filesystem)
9.28 UDF - Universal Disk Format (DVD-ROM filesystem)
9.29 UFS
9.30 VxFS - Veritas filesystem (HP-UX, SCO UnixWare, Solaris)
9.30.1 VxTools
9.31 XFS - Extended filesystem (IRIX)
9.32 Xia FS
10. Raw partitions
11. Appendix
11.1 Network filesystems
11.1.1 AFS - Andrew Filesystem
11.1.2 CODA
11.1.3 NFS - Network filesystem (Unix)
11.1.4 NCP - NetWare Core Protocol (Novell NetWare)
11.1.5 SMB - Session Message Block (Windows 3.x/9x/NT)
11.2 Encrypted filesystems
11.2.1 CFS
11.2.2 TCFS
11.2.3 SFS
11.2.4 VS3FS: Steganographic File System for Linux
11.3 Writing your own filesystem driver
11.3.1 DOS
11.3.2 OS/2
11.3.3 Windows NT
11.4 Related documents
______________________________________________________________________
1. Introduction
The Filesystems HOWTO is about filesystems and accessing filesystems
from various OS. Although this document has been put together to the
best of my knowledge, it may and probably does contain mistakes.
Please if you find some mistake or outdated information, let me know.
I will try to keep this document up to date and as error free as
possible. Any contributions are also welcome, so if you want to write
anything about filesystems, please contact me via e-mail.
Before you read this HOWTO it's recommended to read Stein Gjoen's
Disk-HOWTO (you can obtain it from
<
http://sunsite.unc.edu/LDP/HOWTO/> ).
This HOWTO can be obtained from <
http://penguin.cz/~mhi/fs/> or
<
http://metalab.unc.edu/filesystems/howto/>.
If you are Japanese user, you might be interested that FUJIWARA
Teruyoshi translated this HOWTO to Japanese. It is available at
<
http://www.linux.or.jp/JF/JFdocs/Filesystems-HOWTO.html>. SGML
source file can be downloaded from
<
ftp://ftp.linet.gr.jp/pub/JF/sgml/Filesystems-HOWTO.sgml.gz>.
1.1. Copyright
The Filesystems HOWTO, Copyright (c) 1999 Martin Hinner
<
[email protected]>.
This HOWTO is free document; you can redistribute it and/or modify it
under the terms of the GNU General Public License as published by the
Free Software Foundation; either version 2 of the License, or (at your
option) any later version.
This HOWTO is distributed in the hope that it will be useful, but
WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
General Public License for more details.
You should have received a copy of the GNU General Public License
along with this document or GNU CC; if not, write to the: Free
Software Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
1.2. Filesystems mailing-list
You may want to join Filesystems mailing list. It's intended to be a
good source of information for both end-users and developers. So if
you have anything to do with filesystems, join ;-) To subscribe send
email to <
[email protected]> and in the BODY (not the subject) of
the email message put (without quotes): "subscribe fs-l".
1.2.1. Linux kernel filesystems mailing-list
To join Linux kernel filesystems mailing list linux-
[email protected], send e-mail to
[email protected]. Put
"subscribe linux-fsdev" in message body.
1.2.2. FreeBSD filesystems mailing-list
To join techical FreeBSD filesystems mailing list freebsd-
[email protected], send e-mail to
[email protected]. Put "subscribe
freebsd-fs" in message body.
1.3. Filesystems collection at metalab.unc.edu
Filesystems collection is FTP/WWW site providing useful information
about filesystems and filesystem-related programs and drivers. It
lives at <
http://metalab.unc.edu/filesystems/>, or FTP-only at
<
ftp://metalab.unc.edu/pub/docs/filesystems/>.
1.4. Credits
The original "Filesystems access HOWTO" was written by Georgatos
Photis (see his homepage at <
http://students.ceid.upatras.gr/~gef/>).
This HOWTO contains a lot of information from his webpage. Thanks,
Gef.
FUJIWARA Teruyoshi <
[email protected]> translated this HOWTO to
Japanese.
Other people who have contributed or helped me (directly or
indirectly) with this HOWTO are, in alphabetical order:
o Remy Card <
[email protected]> - Ext2 filesystem introduction
o Peter A. Dinda <
[email protected]> - HFS filesystem description
o Alfonso De Gregorio <
[email protected]> - TCFS filesystem info
o Radek Machacka <
[email protected]> - Thanks for SCO UnixWare and SCO
OpenServer
o Peter Todd <
[email protected]> - SFS filesystem info
o Theodore Ts'o <
[email protected]> - Ext2 filesystem introduction
o Stephen Tweedie <
[email protected]> - Ext2 filesystem introduction
Many thanks to the above people. If I have forgotten anyone, please
let me know.
1.5. Filesystems accessibility map
This is filesystem accessibility "map", alphabetically ordered by
operating system. You may find this list a little bit chaotic. It's
because Linux sgmltools don't know tables.
YOU SEE THAT THIS `MAP' IS NOT STILL COMPLETE. I WILL TRY TO FINISH
IT IN THE NEAR FUTURE.
FreeBSD: ``BSD FFS'' | ``Ext2'' | ``HPFS'' | ``NTFS''
Linux: ``AFFS''| ``BeFS''| ``BFS''| ``Ext2 FS''| ``BSD FFS''|
``HPFS''| ``Qnx4 FS''| ``Xia''
NetBSD: ``BSD FFS'' | ``FAT12/16'' | ``ISO9660''
NetWare 2.x: ``NWFS-286''
NetWare 3.x, 4.x: ``NWFS-386'' | ``ISO9660''
NetWare 5.x: ``NWFS-386'' | ``NSS'' | ``ISO9660''
OpenBSD: ``BSD FFS'' | ``FAT12/16''
OS/2: ``Ext2 FS'' | ``FAT12/16/32'' | ``HPFS'' | ``HPFS'' | ``ISO
9660'' | ``JFS'' | ``VFAT''
QNX 4: ``FAT12/16'' | ``ISO 9660'' | ``Qnx4 FS''
SCO OpenServer: ``AFS''| ``DTFS''| ``EAFS''| ``HTFS''| ``ISO 9660'' |
``S51K''
SCO UnixWare: ``BFS''| ``DTFS''| ``ISO 9660'' | ``System V''| ``VxFS''
1.6. Introduction to contiguous allocation filesystems
Some contiguous filesystems: ``BFS'', ``ISO9660 and extensions''.
1.7. Introduction to linked-list allocation filesystems
1.8. Introduction to FAT-based filesystems
(todo)
Some FAT filesystems: ``FAT12/16/32, VFAT'' and ``NetWare filestem''.
1.9. Introduction to Inode filesystems
(todo)
1.10. Introduction to extent filesystems
(todo)
Some 'extent' filesystems: ``EFS'' and ``VxFS''.
1.11. Introduction to filesystems using balanced trees
(todo)
Some filesystems which use B+ trees: ``HFS'', ``NSS'', ``Reiser FS''
and ``Spiralog filesystem''.
1.12. Introduction to logging/journaling filesystems
File systems update their structural information (called metadata) by
synchronous writes. Each metadata update may require many separate
writes, and if the system crashes during the write sequence, metadata
may be in inconsistent state.
At the next boot the filesystem check utility (called fsck) must walk
through the metadata structures, examining and repairing them. This
operation takes a very very long time on large filesystems. And the
disk may not contain sufficient information to correct the structure.
This results in misplaced or removed files.
A journaling file system uses a separate area called a log or journal.
Before metadata changes are actually performed, they are logged to
this separate area. The operation is then performed. If the system
crashes during the operation, there is enough information in the log
to "replay" the log record and complete the operation.
This approach does not require a full scan of the file system,
yielding very quick filesystem check time on large file systems,
generally a few seconds for a multiple-gigabyte file system. In
addition, because all information for the pending operation is saved,
no removals or lost-and-found moves are required. Disadvantage of
journaling filesystems is that they are slower than other filesystems.
Some journaling filesystems: ``BeFS'', ``HTFS'', ``JFS'', ``NSS'',
``Spiralog filesystem'', ``VxFS'' and ``XFS''.
1.13. Other filesystem features
1.13.1. Quota
1.13.2. Snapshot
1.13.3. ACLs
2. Volumes
2.1. PC Partitions
o <
http://www.win.tue.nl/~aeb/partitions/> Partition types document
by Andries Brouwer <
[email protected]>
2.1.1. GNU parted
o Homepage: <www.alphalink.com.au/~clausen/parted/>
o Download: <
ftp://ftp.gnu.org/gnu/parted/>
o Authors: Andrew Clausen <
[email protected]>, Lennert
Buytenhek <
[email protected]> and Matt Wilson <
[email protected]>.
o Bug reports: <
[email protected]>,
o Access: varies for each filesystem, see below.
o License: GPL
GNU parted can create, destroy, resize, copy and move partitions,
and the filesystems on them. It currently supports ``Ext2'',
``FAT16'', ``FAT32'' and Linux-swap.
Filesystem detect create resize copy check
ext2 * * *1
fat * * *2 *2 *
linux-swap * * * *
NOTES:
1 Limited checking is done when the filesystem is opened. This is the
only checking at the moment. All commands (including resize) will
gracefully fail, leaving the filesystem in tact, if there is are any
errors in the file system (and the vast majority of errors in
general).
2 The size of the new partition, after resizing or copying, is
restricted by the cluster size. This is worse than you think, because
you don't get to choose your cluster size (it's a bug in Windows, and
you want compatibility, right?).
2.1.2. Repairing corrupted partition table
2.1.2.1. Fixdisktable
o Homepage: <
http://bmrc.berkeley.edu/people/chaffee/fat32.html>
o Download: ?
o Author: ?
o Access: ?
o License: ?
This is a utility that handles ext2, FAT, NTFS, ufs, BSD disklabels
(but not yet old Linux swap partitions); it actually will rewrite
the partition table, if you give it permission.
2.1.2.2. gpart
o Homepage: <
http://home.pages.de/~michab/gpart/>
o Download: ?
o Author: ?
o Access: ?
o License: ?
GPART is a utility that handles ext2, FAT, Linux swap, HPFS, NTFS,
FreeBSD and Solaris/x86 disklabels, minix, reiser fs; it prints a
proposed contents for the primary partition table, and is well-
documented.
2.1.2.3. rescuept
o Homepage: util-linux ?
o Download: ?
o Author: ?
o Access: ?
o License: ?
Recognizes ext2 superblocks, FAT partitions, swap partitions, and
extended partition tables; it may also recognize BSD disklabels and
Unixware 7 partitions. It prints out information that can be used
with fdisk or sfdisk to reconstruct the partition table. It is in
the non-installed part of the util-linux distribution.
2.1.2.4. findsuper
o Homepage: e2progs ?
o Download: ?
o Author: ?
o Access: ?
o License: ?
Small utility that finds blocks with the ext2 superblock signature,
and prints out location and some info. It is in the non-installed
part of the e2progs distribution.
2.2. Other partitions
Because I use only Intel x86 machines, any contributions (or non-x86
machine donation ;-) ) are very welcome. If you can provide any useful
information, don't hesitate to mail me.
2.2.1. ADFS partitions
2.2.2. Amiga partitions
2.2.3. ATARI partitions
2.2.4. Macintosh partitions
2.2.5. OSF partitions
2.2.6. Sun partitions
2.2.7. Ultrix partitions
2.3. Unix disklabels
(todo)
2.3.1. BSD disklabel
(todo)
2.3.2. UnixWare disklabel
UnixWare VTOC (Volume Table Of Contents) divides disk partition to 16
logical partitions. Linux kernel supports UnixWare VTOC, you must
check "UnixWare slices support (EXPERIMENTAL)" and recompile your
kernel. Another way of reading UnixWare disklabel is using GPL port
of prtvtoc(1) command, which is in ``vxtools'' package.
2.3.3. SCO OpenServer disklabel
(todo)
2.3.4. Sun Solaris disklabel
(todo)
2.4. Windows NT volumes
o Homepage: <
http://www.penguin.cz/~mhi/fs/vol/>
o Author: Martin Hinner <
[email protected]>
o Access: Read-only, supports OS/2 Volumes, Windows NT Stripe sets
and volumes.
o Download: <
ftp://ftp.penguin.cz/pub/users/mhi/vol/>
o License: GPL
This linux-kernel driver allows you to access and mount linear and
stripe set volumes.
2.4.1. Repairing "fault tolerant" NTFS disks using FTEdit
o Homepage: ? MS ARTICLE ID: Q131658
o Download: <
ftp://ftp.rhrz.uni-
bonn.de/pub/pc/winnt/intel/ftedit.zip>
o Author: Microsoft Corp.
o License: ?
If you have a Windows NT Workstation or Server configured for fault
tolerant (FT) partitions (such as stripes with parity and volume
sets), and those partitions are inaccessible and appear in Disk
Administrator as type Unknown, you can possibly make them
accessible again by using the utility FTEDIT.
2.5. MD - Multiple Devices driver for Linux
o Homepage:?
o Author: Marc Zyngier <
[email protected]>
o Access: Read-write, supports linear mode, RAID-1, RAID-4 and
RAID-5.
o Download: Linux kernel, tools are available at <
ftp://sweet-
smoke.ufr-info-p7.ibp.fr/public/Linux/>
o License: GPL
This driver lets you combine several hard disk partitions into one
logical block device. This can be used to simply append one
partition to another one or to combine several redundant hard disks
to a RAID1/4/5 device so as to provide protection against hard disk
failures. This is called "Software RAID" since the combining of the
partitions is done by the kernel.
2.6. LVM - Logical Volume Manager (HP-UX LVM?)
Linux implementation is available here:
o Homepage: <
http://linux.msede.com/lvm/>
o Author: Heinz Mauelshagen <
[email protected]>
o Access: ?
o Download: <
ftp://linux.msede.com/lvm/v0.6/>
o License: GPL
2.7. VxVM - Veritas Volume Manager
For more information about Veritas Volume Manager see
<
http://www.veritas.com/>.
See also: ``VxFS (Veritas Journaling Filesystem)''.
2.8. IBM OS/2 LVM
Logical Volume Manager is available in OS/2 WarpServer 5. It allows
you to create linear volumes on several disks/partitions. Some people
say that it's compatible with IBM AIX Logical Volume Manager.
See also: ``HPFS'', ``JFS''
2.9. StackVM
StackVM is CrosStor's volume manager. Using StackVM the administrator
can combine multiple physical disk slices into a single logical device
know as a vdisk. Vdisk is short for virtual disk. The physical disks
can be combined to form a concatenation, RAID 0 (stripe), RAID 1
(mirror), RAID 4 or RAID 5. In addition a single disk partition can be
subdivided into multiple simple vdisks. For more information see
CrosStor homepage at <
http://www.crosstor.com/>.
2.10. Novell NetWare volumes
NetWare volumes are used for NWFS-386 filesystem.
3. DOS FAT 12/16/32, VFAT
3.1. VFAT: Long filenames
Windows 95/98 and Windows NT/2000 store long filenames on FAT in
special directory entries with set attributes ReadOnly, Hidden, System
and Volume, so if you access FAT volume from DOS you don't see these
"files". These special entries have this mad structure:
byte sequence number for slot
string(10) first 5 characters in name
byte attribute byte
byte always 0
byte checksum for 8.3 alias
string(12) 6 more characters in name
word starting cluster number, 0 in long slots
string(4) last 2 characters in name
Problem occur when you delete or modify file with long name from
system without VFAT support, because only DOS 8+3 entry will be
deleted or modified. Scandisk from Windows 95/98 can repair this
problem.
3.2. UMSDOS: Linux LFN/attributes on FAT filesystem
Linux has it's own FAT extensions which gives you long filenames,
permissions and owners, links and special devices on FAT partition,
called UMSDOS. Each directory contains file named "--linux-.---".
There are stored long names and other necessary fields. For more
information see file
/usr/src/linux/Documentation/filesystems/umsdos.txt. Author of Linux
umsdos driver is Jacques Gelinas <
[email protected]> and it is
currently maintained by Matija Nalis <
[email protected]>.
3.3. OS/2 Extended Attributes on FAT filesystems
OS/2 Warp version 3,4 and 5 stores long filenames and extended
attributes on FAT volume in files "\ea data. sf" and "\wp root. sf"
(both files are in root directory of filesystem). AFAIK there is no
known implementation of OS/2 EAs for any other OS. If you can supply
any information about EA structure, don't hesitate to mail them to me.
3.4. Star LFN
Star LFN is an emulator that allows programs, running under DOS 4.0 or
above, to use the long filename functions present in Windows'95 DOS
boxes. Currently, it can only read and write long filenames from and
into a system+hidden file, which means you can't either read or write
real Windows'95 long filenames. For more information see
<
http://c64.rulez.org/~sta/starlfn.html>.
3.5. Accessing VFAT from OS/2 (VFAT-OS2)
o Homepage: <
http://www.dsteiner.com/products/software/os2/ifs.htm>
o Author: Daniel Steiner <
[email protected]>
o Access: Read-Write, no EAs supported.
o Mirror: <
ftp://hobbes.nmsu.edu/pub/os2/system/drivers/filesys/>
o License: GPL
VFAT-OS2 is a package that will allow OS/2 to seamlessly access
Windows 95 VFAT formatted partitions from OS/2 as if they were
standard OS/2 drive letters. The ultimate aim of this package is to
be able to use the VFAT file system as a replacement of FAT. It can
now also access NTFS partitions in read-only mode.
3.6. Accessing VFAT from DOS (LFNDOS driver)
Some people say that Microsoft has released a driver called LFNDOS
that provides the Microsoft Long Filename API under DOS. If you know
where can this driver be downloaded, send me e-mail please.
3.7. Accessing VFAT from DOS (Free LFNDOS driver)
o Homepage: <
http://members.xoom.com/dosuser/>
o Author: Chris Jones <
[email protected]>
o Access: Read-Write
o Mirror:
<
http://www.simtel.net/pub/simtelnet/msdos/fileutil/lfnds106.zip>
o License: Free, source code available
LFNDOS provides the Windows95 Long Filename (LFN) API to DOS
programs. It uses the same format for storing the names on disk as
Windows95 does, so you can view and use long filenames under both
systems interchangeably. It runs as a memory-resident program, and
while resident requires about 60k of conventional memory.
Under Windows95, a DOS program can use long filenames by calling a set
of interrupt functions, which Windows provides. For example,
COMMAND.COM will allow long filenames when run as a DOS Prompt from
Windows, but not if you restart in MS-DOS mode. Other programs such as
EDIT.COM and all DJGPP programs use long filenames if available.
3.8. Accessing VFAT from DOS (Odi's LFN tools)
o Homepage: <
http://odi.webjump.com/>
o Author: Ortwin Glueck <
[email protected]>
o Access: Read-Write, only DOS utilities
o Mirror:
<
http://www.simtel.net/pub/simtelnet/msdos/fileutil/lfn141.zip>
o License: ?
These tools provide easy file management under DOS with long
filenames created by Windows 95/98 on FAT32, FAT16 and FAT12 file
systems. Typing LDIR brings up the directory with its long
filenames. Copying a file with LCOPY preserves long filenames. You
can even create directories (LMD) with long names or rename files
(LREN) with long names.
3.9. Accessing FAT32 from OS/2 (FAT32.IFS)
o Homepage: <
http://www.os2ss.com/information/kelder/index.html>
o Author: Henks Kelder <
[email protected] >
o Access: Read-Write, long filenames, no EAs support.
o Download: <
http://www.os2ss.com/information/kelder/os2fat32.zip>
o License: Free
FAT32.IFS for OS/2 will allow you to access FAT32 partitions from
OS/2. You cannot create FAT32 partitions, you'll still need Win95
OSR2 to do that. Also, OS/2s CHKDSK cannot fix all possible errors
that can occur, you'll have to use Windows 95 Scandisk to fix
certain errors.
3.10. Accessing FAT32 from Windows NT 4.0
o Download: <
http://www.chat.ru/~ashedel/fat32/fastfat32.rar>
o Author: Anonymous
o License: Free or GPL ?
FAT32 filesystem driver for NT 4.0 and NT 3.51.
3.11. Accessing FAT32 from Windows NT 4.0
o Homepage: <
http://www.sysinternals.com/fat32.htm>
o Author: Mark Russinovich <
[email protected]> and Bryce Cogswell
<
[email protected]>.
o Access: Read-only in free version, RW in commercial.
o Download: ?
o License: Free(read-only) or Commercial(read-write)
This is a FAT32 file system driver for Windows NT(R) 4.0. Once
installed, any FAT32 drives present on your system will be fully
accessible as native Windows NT volumes. Free version provides
read-only capabilities. A read/write version is for sale.
3.12.
Accessing Stac/Dblspaced/Drvspaced drives from Linux (DMSDOS)
o Homepage: <
http://fb9nt.uni-
duisburg.de/mitarbeiter/gockel/software/dmsdos/>
o Author: Frank Gockel <
[email protected]> and Pavel Pisa
<
[email protected]>
o Access: Stacker, Dblspace and Drvspace in Read-Write mode, long
filenames.
o Download: <
ftp://fb9nt.uni-duisburg.de/pub/linux/dmsdos/>
o Freshmeat: Console/Filesystems
o License: GPL
DMSDOS reads and writes compressed DOS filesystems (CVF-FAT). The
following configurations are supported:
o DoubleSpace / DriveSpace (MS-DOS 6.x)
o DoubleSpace / DriveSpace (Windows 95)
o DriveSpace 3 (Windows 95 with Plus! pack)
o Stacker 3
o Stacker 4
It works with FAT32, NLS, codepages (tested with fat32 patches
version 0.2.8 under Linux 2.0.33 and with fat32 in standard 2.1.xx
kernels and 2.0.34+35). Dmsdos can run together with vfat or umsdos
for long filenames. It has been redesigned to be ready for SMP and
should now compile completely under libc6.
3.13.
Accessing Dblspaced/Drvspaced drives from Linux (thsfs)
o Download: <
ftp://ftp.ai-lab.fh-
furtwangen.de/pub/os/linux/local/thsfs.tgz>
o Author: Thomas Scheuermann <
[email protected]>
o Access: Dblspace and Drvspace in Read-only mode.
o License: See copyright on files. Basically free
3.14. Fsresize - FAT16/32 resizer
o Homepage: <
http://www.alphalink.com.au/~clausen/fsresize/>
o Author: Andrew Clausen <
[email protected]>
o Download:
<
http://www.alphalink.com.au/~clausen/fsresize-0.8.tar.gz>
o Freshmeat: Console/Filesystems
o Access: Read/Write, full FAT16/FAT32 support
o License: GPL
Resizes FAT16/FAT32 filesystems. It doesn't require any other
programs (like a defrager). It has --backup and --restore options,
so if there's a power failure, (or a bug), you can always go back.
The backup files are usually < 1 meg.
The author probably won't be releasing any more versions of fsresize,
because he is working on parted - a Partition Magic clone. It will be
able to resize, copy, create and check filesystems/partitions.
3.15. FIPS - FAT16 resizer
o Homepage: ?
o Author: Arno Schaefer <
[email protected]>
o Download:
<
ftp://sunsite.unc.edu/pub/Linux/system/Install/fips01alpha.tar.z>
o License: GPL
4. High Performance FileSystem (HPFS)
Good HPFS links:
o <
ftp://ftp.leo.org/pub/comp/os/os2/leo/doc/hpfsinf.zip>
o <
ftp://hobbes.nmsu.edu/pub/os2/info/tips/hpfs.zip>
o <
http://www.globalxs.nl/home/c/cyborg/index.html> - a good page
about HPFS accessibility
o <
http://www-4.ibm.com/software/os/warp/warp-server/warp-server-
adv/c2j.html> - IBM OS/2 Warp Server : Features & Benefits : File &
Print
4.1. Accessing HPFS from DOS (iHPFS)
o Homepage: <
http://www.student.nada.kth.se/~f96-bet/ihpfs/>
o Author: Marcus Better
[email protected]
o Download:
<
http://www.student.nada.kth.se/~f96-bet/ihpfs/ihpfs128.zip>
o Access: Read-only
o License: GPL
iHPFS makes possible for OS/2 users to use their HPFS partitions when
they boot plain DOS. The HPFS partition is assigned a drive letter,
and can be accessed like any DOS drive.iHPFS is restricted to read-
only access.
This program is no longer being developed, because author doesn't use
OS/2. If you are willing to maintain the program, let him know.
4.2. Accessing HPFS from DOS (hpfsdos)
o Homepage: ?
o Author: Robert Muchsel <
[email protected]> (this e-mail doesn't
work)
o Access: Read-only
o License: Shareware ($23)
4.3. Accessing HPFS from DOS (hpfsa)
o Homepage: <
http://www.student.informatik.th-
darmstadt.de/~akinzler/>
o Author: Andreas Kinzler <
[email protected]>
(this email doesn't work)
o Download: <
ftp://ftp.cdrom.com/.1/os2/mdos/hpfsa102.zip>
o Access: Read/Write
o License: Shareware ($40)
4.4. Accessing HPFS from DOS (amos)
o Homepage: ?
o Author: Allan Mertner <
[email protected]> (this email doesn't
work)
o Download: <
ftp://hobbes.nmsu.edu/pub/dos/amos320.zip>
o License: Shareware ($50)
4.5. Accessing HPFS from Linux
o Homepage:
<
http://artax.karlin.mff.cuni.cz/~mikulas/vyplody/hpfs/index-e.cgi>
o Download:
<
http://artax.karlin.mff.cuni.cz/~mikulas/vyplody/hpfs/hpfs-0.99b.tar.gz>
for 2.0 kernels; and
<
http://artax.karlin.mff.cuni.cz/~mikulas/vyplody/hpfs/hpfs-1.98b.tar.gz>
for 2.2 kernels
o Author: Mikulas Patocka <
[email protected] >
o Access: Read-Write, extended attributes, long names.
o License: GPL
This driver is part of Linux kernel (2.1.x+). It can read and write
to HPFS partions. Access rights and owner can be stored in extended
attributes. Few bugs in original read-only HPFS are corrected. It
supports HPFS386 on Warp Server Advanced.
If you have kernel with HPFS support, say "Y"es to 'OS/2 HPFS
filesystem support' in Filesystems submenu. Then recompile kernel
using 'make dep bzImage', reboot and try to mount your HPFS partition
(e.g. mount /dev/hda2 /mnt -t hpfs).
4.6. Accessing HPFS from FreeBSD
o Homepage: <
http://iclub.nsu.ru/~semen/>
o Download: <
http://iclub.nsu.ru/~semen/hpfs/hpfs-0.3b.tar.gz>
o Author: Semen A. Ustimenko <
[email protected] >
o Access: Read/Only
o License: BSD
Driver allows to mount HPFS volume into Unix namespace. ReadOnly
access is only supported for now.
4.7. Accessing HPFS from Windows NT 3.5
o Homepage: <
http://www.htc.net/~nbehnken/>
o Download: <
http://www.htc.net/~nbehnken/hpfs_nt.zip>
o Author: Chris Behnken <
[email protected] >
o License: Freeware
This program will edit the Windows NT registry and enable HPFS
support. Pinball.sys is the HPFS filesystem driver for Windows NT.
It can be found on NT 3.5x's CD-ROM. Microsoft no longer supports
HPFS. Installing this program will void your warranty and possibly
the license agreement.
4.8. Accessing HPFS from Windows NT 4
o Download: <
ftp://hobbes.nmsu.edu/pub/windows/hpfsnt.zip>
o Author: ?
o License: ?
HPFS driver for Windows NT 4.0
5. New Technology FileSystem (NTFS)
References:
o <
http://www.microsoft.com/msj/1198/ntfs/ntfstop.htm> NTFS 5
information
o Rajeev Nagar, Windows NT File System Internals (O'Reilly).
o Helen Custer, Inside the Windows NT File System, ISBN:
1-55615-660-X.
o NTFS documentation by Regis Duchesne <
[email protected]>,
<
http://www.via.ecp.fr/~regis/ntfs.tar.bz2> or
<
http://celine.via.ecp.fr/~regis/ntfs/new>
o Microsoft TechNet, February 97, Windows NT Training: Support, NTFS
o <
http://www.stat.math.ethz.ch/~maechler/NTFS-docu>
5.1. Accessing NTFS from DOS (NTFSDOS.EXE)
o Homepage:
http://www.sysinternals.com/ntfs20.htm
o Authors: Mark Russinovich <
[email protected]> and Bryce
Cogswell <
[email protected]>.
o Access: Read-only, Long filenames under DOS 7 and Win9x.
NTFSDOS.EXE is a network file system redirector for DOS/Windows
that is able to recognize and mount NTFS drives for transparent
access. It makes NTFS drives appear indistinguishable from
standard FAT drives, providing the ability to navigate, view and
execute programs on them from DOS or from Windows, including from
the Windows 3.1 File Manager and Windows 95 Explorer.
5.2. Accessing NTFS from DOS (ntpwd)
o Homepage: <
http://www.esiea.fr/public_html/Christophe.GRENIER/>
o Author: Grenier Christophe <
[email protected] >
o Access: Read-only (rw experimental), long filenames supported, no
driver letter (dos tools)
o License: GPL
NTPwd contains command line tools to access NTFS partition, it'a a Dos
port of the driver used by Linux. It contains too a little utility to
change NT password.
5.3. Accessing NTFS from OS/2
o Homepage: <
http://www.dsteiner.com/products/software/os2/ifs.htm>
o Mirror: <
ftp://ftp-
os2.nmsu.edu/pub/os2/system/drivers/filesys/ntfs_003.zip>,
<
ftp://ftp.leo.org/pub/comp/os/os2/leo/drivers/ifs>
o Author: Daniel Steiner <
[email protected] >
o Access: Read-only, Long filenames supported
ntfs_003.zip archive contains only command line tools to acccess a
NTFS partition in OS/2. A true IFS for accessing NTFS is included
in ``VFAT-OS2'' v0.05.
5.4. Accessing NTFS from Linux
o Homepage: <
http://www.informatik.hu-berlin.de/~loewis/ntfs/>
o Author: Martin von Lwis
[email protected]
o Freshmeat: Console/Filesystems
o Homepage: <
http://www.informatik.hu-berlin.de/~loewis/ntfs/ntfs-
current.tgz>
o Mirror: Included in official Linux kernel
o Access: RO, experimental RW, compression, no encryption
o License: GPL
Works both as a kernel driver, as well as a set of command line
utilities.
5.5. Accessing NTFS from FreeBSD and NetBSD
o Homepage: <
http://iclub.nsu.ru/~semen/ntfs/>
o Author: Semen A. Ustimenko <
[email protected]
<mailto:
[email protected]>>
o Download: As part of FreeBSD (
<
ftp://ftp.FreeBSD.org/pub/FreeBSD/>), and NetBSD (
<
ftp://ftp.NetBSD.org/pub/NetBSD/>)
o Mirror: Lookup for FreeBSD's and NetBSD's mirrors
o Access: Read + limited writing, doesn't support codepages
o License: BSD
Driver allows to mount NTFS volumes under FreeBSD and NetBSD. We
also support limited writing ability: you can write into not
comressed files without holes, but you can't change the size of
file yet. Write support was made to swap on NTFS volume.
5.6. Accessing NTFS from BeOS
o Homepage: <
http://www.cs.tamu.edu/people/tkg0143/be/>
o Author: Travis Geiselbrecht <
[email protected] >
o Download:
<
http://www.cs.tamu.edu/people/tkg0143/be/downloads/ntfs-0.05-x86-r4.zip>
o Access: ?
o License: Free
This is a ALPHA version of a NTFS driver for BeOS. It is not the
most polished thing in the world, but every release that author
puts out is more stable than the last. He just implemented
compressed file reads, so be careful with those. He also finally
worked with NTFS 5 volumes, and managed to root out a few bugs.
Author now works for Be Inc, so you will not see his NTFS and ext2
filesystem support updated on the web much more. The drivers will be
pulled into future BeOS releases.
5.7. Accessing NTFS from BeOS (another)
o Homepage:
http://www.sw.com.sg/solutions/ntfs-ro.shtml
o Author: Standard & Western Software,
http://www.sw-soft.com
o Download:
http://download.sw.com.sg/pub/Be/ntfs-rod-0302.tar.gz
o Access: Read-only.
5.8. Repairing NTFS using NTFSDOS Tools
o Homepage: <
http://www.sysinternals.com/>
o Author: Winternals Software <
[email protected]>
o Access: Read-Write: Copy and replace files.
o License: Commercial
An add-on to NTFSDOS that allows one to rename existing files, or
to overwrite a file with new data. Very limited functionality.
5.9. Repairing NTFS using NTRecover
o Homepage: <
http://www.sysinternals.com/>
o Author: Winternals Software <
[email protected]>
o Access: Freeware version is read-only, commercial version is
read/write.
o License: Freeware read-only version, commercial read/write version
Uses a boot floppy and a serial connection to a second NT system to
provide full access to a NTFS drives on dead NT systems. Ideal for
salvaging data or replacing drivers.
6. Extended filesystems (Ext, Ext2, Ext3)
Extended filesystem (ext fs), second extended filesystem (ext2fs) and
third extended filesystem (ext3fs) were designed and implemented on
Linux by Rmy Card, Laboratoire MASI--Institut Blaise Pascal,
<
[email protected]>, Theodore Ts'o, Massachussets Institute of
Technology, <
[email protected]> and Stephen Tweedie, University of
Edinburgh, <
[email protected]>
o <
http://web.mit.edu/tytso/www/linux/ext2.html> - The ext2 homepage.
This is the primary source of information about ext2.
o <
http://uranus.it.swin.edu.au/~jn/explore2fs/es2fs.htm> - Document
about ext2fs from John Newbigin.
o <
http://www.ing.umu.se/~bosse/> - Ext2fs_Rec (ext2 recognizer for
WinNT).
6.1. Extended filesystem (ExtFS)
This is old filesystem used in early Linux systems.
6.2. Second Extended Filesystem (Ext2 FS)
The Second Extended File System is probably the most widely used
filesystem in the Linux community. It provides standard Unix file
semantics and advanced features. Moreover, thanks to the optimizations
included in the kernel code, it is robust and offers excellent
performance.
Since Ext2fs has been designed with evolution in mind, it contains
hooks that can be used to add new features. Some people are working on
extensions to the current filesystem: access control lists conforming
to the Posix semantics, undelete, and on-the-fly file compression.
Ext2fs was first developed and integrated in the Linux kernel and is
now actively being ported to other operating systems. An Ext2fs server
running on top of the GNU Hurd has been implemented. People are also
working on an Ext2fs port in the LITES server, running on top of the
Mach microkernel and in the VSTa operating system. Last, but not
least, Ext2fs is an important part of the Masix operating system,
currently under development by one of the authors.
6.2.1. Motivations
The Second Extended File System has been designed and implemented to
fix some problems present in the first Extended File System. Our goal
was to provide a powerful filesystem, which implements Unix file
semantics and offers advanced features.
Of course, we wanted to Ext2fs to have excellent performance. We also
wanted to provide a very robust filesystem in order to reduce the risk
of data loss in intensive use. Last, but not least, Ext2fs had to
include provision for extensions to allow users to benefit from new
features without reformatting their filesystem.
6.2.2. ``Standard'' Ext2fs features
The Ext2fs supports standard Unix file types: regular files,
directories, device special files and symbolic links.
Ext2fs is able to manage filesystems created on really big partitions.
While the original kernel code restricted the maximal filesystem size
to 2 GB, recent work in the VFS layer have raised this limit to 4 TB.
Thus, it is now possible to use big disks without the need of creating
many partitions.
Ext2fs provides long file names. It uses variable length directory
entries. The maximal file name size is 255 characters. This limit
could be extended to 1012 if needed.
Ext2fs reserves some blocks for the super user (root). Normally, 5% of
the blocks are reserved. This allows the administrator to recover
easily from situations where user processes fill up filesystems.
6.2.3. ``Advanced'' Ext2fs features
In addition to the standard Unix features, Ext2fs supports some
extensions which are not usually present in Unix filesystems.
File attributes allow the users to modify the kernel behavior when
acting on a set of files. One can set attributes on a file or on a
directory. In the later case, new files created in the directory
inherit these attributes.
BSD or System V Release 4 semantics can be selected at mount time. A
mount option allows the administrator to choose the file creation
semantics. On a filesystem mounted with BSD semantics, files are
created with the same group id as their parent directory. System V
semantics are a bit more complex: if a directory has the setgid bit
set, new files inherit the group id of the directory and
subdirectories inherit the group id and the setgid bit; in the other
case, files and subdirectories are created with the primary group id
of the calling process.
BSD-like synchronous updates can be used in Ext2fs. A mount option
allows the administrator to request that metadata (inodes, bitmap
blocks, indirect blocks and directory blocks) be written synchronously
on the disk when they are modified. This can be useful to maintain a
strict metadata consistency but this leads to poor performances.
Actually, this feature is not normally used, since in addition to the
performance loss associated with using synchronous updates of the
metadata, it can cause corruption in the user data which will not be
flagged by the filesystem checker.
Ext2fs allows the administrator to choose the logical block size when
creating the filesystem. Block sizes can typically be 1024, 2048 and
4096 bytes. Using big block sizes can speed up I/O since fewer I/O
requests, and thus fewer disk head seeks, need to be done to access a
file. On the other hand, big blocks waste more disk space: on the
average, the last block allocated to a file is only half full, so as
blocks get bigger, more space is wasted in the last block of each
file. In addition, most of the advantages of larger block sizes are
obtained by Ext2 filesystem's preallocation techniques.
Ext2fs implements fast symbolic links. A fast symbolic link does not
use any data block on the filesystem. The target name is not stored in
a data block but in the inode itself. This policy can save some disk
space (no data block needs to be allocated) and speeds up link
operations (there is no need to read a data block when accessing such
a link). Of course, the space available in the inode is limited so not
every link can be implemented as a fast symbolic link. The maximal
size of the target name in a fast symbolic link is 60 characters. We
plan to extend this scheme to small files in the near future.
Ext2fs keeps track of the filesystem state. A special field in the
superblock is used by the kernel code to indicate the status of the
file system. When a filesystem is mounted in read/write mode, its
state is set to ``Not Clean''. When it is unmounted or remounted in
read-only mode, its state is reset to ``Clean''. At boot time, the
filesystem checker uses this information to decide if a filesystem
must be checked. The kernel code also records errors in this field.
When an inconsistency is detected by the kernel code, the filesystem
is marked as ``Erroneous''. The filesystem checker tests this to force
the check of the filesystem regardless of its apparently clean state.
Always skipping filesystem checks may sometimes be dangerous, so
Ext2fs provides two ways to force checks at regular intervals. A mount
counter is maintained in the superblock. Each time the filesystem is
mounted in read/write mode, this counter is incremented. When it
reaches a maximal value (also recorded in the superblock), the
filesystem checker forces the check even if the filesystem is
``Clean''. A last check time and a maximal check interval are also
maintained in the superblock. These two fields allow the administrator
to request periodical checks. When the maximal check interval has been
reached, the checker ignores the filesystem state and forces a
filesystem check.
An attribute allows the users to request secure deletion on files.
When such a file is deleted, random data is written in the disk blocks
previously allocated to the file. This prevents malicious people from
gaining access to the previous content of the file by using a disk
editor.
Last, new types of files inspired from the 4.4 BSD filesystem have
recently been added to Ext2fs. Immutable files can only be read:
nobody can write or delete them. This can be used to protect sensitive
configuration files. Append-only files can be opened in write mode but
data is always appended at the end of the file. Like immutable files,
they cannot be deleted or renamed. This is especially useful for log
files which can only grow.
6.2.4. Physical Structure
The physical structure of Ext2 filesystems has been strongly
influenced by the layout of the BSD filesystem. A filesystem is made
up of block groups. Block groups are analogous to BSD FFS's cylinder
groups. However, block groups are not tied to the physical layout of
the blocks on the disk, since modern drives tend to be optimized for
sequential access and hide their physical geometry to the operating
system.
,---------+---------+---------+---------+---------,
| Boot | Block | Block | ... | Block |
| sector | group 1 | group 2 | | group n |
`---------+---------+---------+---------+---------'
Each block group contains a redundant copy of crucial filesystem
control informations (superblock and the filesystem descriptors) and
also contains a part of the filesystem (a block bitmap, an inode
bitmap, a piece of the inode table, and data blocks). The structure of
a block group is represented in this table:
,---------+---------+---------+---------+---------+---------,
| Super | FS | Block | Inode | Inode | Data |
| block | desc. | bitmap | bitmap | table | blocks |
`---------+---------+---------+---------+---------+---------'
Using block groups is a big win in terms of reliability: since the
control structures are replicated in each block group, it is easy to
recover from a filesystem where the superblock has been corrupted.
This structure also helps to get good performances: by reducing the
distance between the inode table and the data blocks, it is possible
to reduce the disk head seeks during I/O on files.
In Ext2fs, directories are managed as linked lists of variable length
entries. Each entry contains the inode number, the entry length, the
file name and its length. By using variable length entries, it is
possible to implement long file names without wasting disk space in
directories.
6.2.5. Performance optimizations
In Linux, the Ext2fs kernel code contains many performance
optimizations, which tend to improve I/O speed when reading and
writing files.
Ext2fs takes advantage of the buffer cache management by performing
readaheads: when a block has to be read, the kernel code requests the
I/O on several contiguous blocks. This way, it tries to ensure that
the next block to read will already be loaded into the buffer cache.
Readaheads are normally performed during sequential reads on files and
Ext2fs extends them to directory reads, either explicit reads
(readdir(2) calls) or implicit ones (namei kernel directory lookup).
Ext2fs also contains many allocation optimizations. Block groups are
used to cluster together related inodes and data: the kernel code
always tries to allocate data blocks for a file in the same group as
its inode. This is intended to reduce the disk head seeks made when
the kernel reads an inode and its data blocks.
When writing data to a file, Ext2fs preallocates up to 8 adjacent
blocks when allocating a new block. Preallocation hit rates are around
75% even on very full filesystems. This preallocation achieves good
write performances under heavy load. It also allows contiguous blocks
to be allocated to files, thus it speeds up the future sequential
reads.
These two allocation optimizations produce a very good locality of:
o related files through block groups
o related blocks through the 8 bits clustering of block allocations.
6.3. Third Extended Filesystem (Ext3 FS)
Ext3 support the same features as Ext2, but includes also Journaling.
You can download pre- version from
<
ftp://ftp.uk.linux.org/pub/linux/sct/fs/jfs/>.
6.4. E2compr - Ext2fs transparent compression
o Homepage: <
http://opensource.captech.com/e2compr/>
o Download: <
ftp://opensource.captech.com/e2compr/>
o Maintainer: Peter Moulder <
[email protected]>
o Freshmeat: Console/Filesystems
o Access: As for ext2 (Read/Write, Long filenames)
o License: GPL except for compression algorithms (various licenses)
Implements `chattr +c' for the ext2 filesystem. Software consists
of a patch to the linux kernel, and patched versions of various
software (principally e2fsprogs i.e. e2fsck and friends). Although
some people have been relying on it for years, THIS SOFTWARE IS
STILL IN DEVELOPMENT, AND IS NOT ,END-USER`-READY.
6.5. Accessing Ext2 from DOS (Ext2 tools)
o Download:
ftp://sunsite.unc.edu/pub/Linux/system/filesystems/ext2/
o Access: Read-only, no drive letters (special utilites)
o Author: Claus Tondering <
[email protected]>
o Access: ?
o License: ?
A collection of DOS programs that allow you to read a Linux ext2
file system from DOS.
6.6. Accessing Ext2 from DOS, Windows 9x/NT and other Unixes (LTools)
o Homepage: <
http://www.it.fht-
esslingen.de/~zimmerma/software/ltools.html>
o Author: Werner Zimmermann <
[email protected]>
o Homepage: <
http://www.it.fht-
esslingen.de/~zimmerma/software/ltools.htm>
o Mirror: <
http://metalab.unc.edu/pub/linux/utils/dos/> (only major
releases)
o Access: Read/Write/Modify, Long filenames
o License: GPL
The LTOOLS are under DOS/Windows 3.x/Windows 9x/Windows NT or non-
Linux-UNIX, what the MTOOLS are under Linux. You can access (read,
write, modify) your Linux files when running one of the other
operating systems. The kernel of the LTOOLS is a set of command
line programs. Additionally a JAVA program as a stand alone
graphical user interface is available. Alternatively, you can use
your standard web browser as a graphical user interface. The LTOOLS
do not only provide access to Linux files on your own machine, but
also remote access to files on other machines.
6.7. Accessing Ext2 from OS/2
o Homepage: <
http://perso.wanadoo.fr/matthieu.willm/ext2-os2/>
o Author: Matthieu WILLM <
[email protected]> ,
<
[email protected]>
o Download:
<
ftp://hobbes.nmsu.edu/pub/os2/system/drivers/filesys/ext2_240.zip>
o Freshmeat: Console/Filesystems
o Access: Read/Write, swapping and booting to/from ext2, removable
media support, but NO extended attributes.
EXT2-OS2 is a package that allows OS/2 to seamlessly access Linux
ext2 formatted partitions from OS/2 as if they were standard OS/2
drive letters. The ultimate aim of this package is to be able to
use the ext2 file system as a replacement of FAT or HPFS. For the
moment the only lacking feature to achieve this goal is the support
for OS/2 extended attributes.
6.8. Accessing Ext2 from Windows 95/98 (FSDEXT2)
o Homepage:
http://www.yipton.demon.co.uk/
o Author: Peter van Sebille
[email protected] ,
[email protected]
o Freshmeat: Console/Filesystems
o Access: Read-only, Long filenames supported
6.9. Accessing Ext2 from Windows 95 (Explore2fs)
o Homepage: <
http://uranus.it.swin.edu.au/~jn/linux/explore2fs.htm>
o Access: Read/Write, Long filenames, symbolic links etc...
o Author: John Newbigin <
[email protected]>
o License: GPL
A user space application which can read and write the second
extended file system ext2. Supports hard disks and removable
media, including zip and floppy. Uses a windows explorer like
interface to show files and details. Supports Drag& Drop, context
menus etc. Written for Windows NT, but has some support for
Windows 95. Large disks can cause problems.
6.10. Accessing Ext2 from Windows NT (ext2fsnt)
o Homepage: <
http://www.chat.ru/~ashedel/ext2fsnt/>
o Download: <
http://www.chat.ru/~ashedel/ext2fsnt/ext2fsnt.rar>
o Author: Andrey Shedel <
[email protected] >
o License: Free
o Access: Read-write, LFN, Security, PageFile, Hardlinks.
6.11. Accessing Ext2 from BeOS
o Homepage: <
http://www.cs.tamu.edu/people/tkg0143/be/>
o Author: Travis Geiselbrecht <
[email protected] >
o Download:
<
http://www.cs.tamu.edu/people/tkg0143/be/downloads/ext2fs-1.0.6-x86-r4.zip>
for R4 and
<
http://www.cs.tamu.edu/people/tkg0143/be/downloads/ext2fs-1.0.3-x86-r3.zip>
for R3.
o Access: Read-only, long filenames supported.
o License: Free
This is a driver to allow BeOS to mount the Linux Ext2 filesystem.
The version that is currently released author consider pretty
stable. People have been using it for a long time, with no bug
reports.
Authow now works for Be Inc, so you will not see his ext2 and NTFS
filesystem support updated on the web much more. The drivers will be
pulled into future BeOS releases.
6.12. Accessing Ext2 from MacOS (MountX)
o Homepage: <
http://calvaweb.calvacom.fr/bh40>
o Author: ?
o Download: ?
MacOS driver which allows you to mount ext2 filesystems (Linux and
MkLinux) on the Macintosh.
6.13. Accessing Ext2 from MiNT
o Homepage: <http://?>
o Author: <
[email protected]>
o Download: ?
o License: GPL
This is a full working Ext2 filesystem driver for FreeMiNT. It can
read and write the actual ext2 version as implemented in Linux for
example. The partition size is not limited and the logical sector
size can be 1024, 2048 or 4096 bytes. The only restriction is that
the physical sector size is smaller or equal to the logical sector
size. The blocksize can be configured if you initialize the
partition with mke2fs.
6.14. Ext2fs defrag
o Download: <
ftp://ftp.uk.linux.org/pub/linux/sct/defrag/>
o Author: Stephen C. Tweedie <
[email protected] >
o License: GPL
Defragments your ext2 filesystem. Needs updated for glib
libraries.
6.15. Ext2fs resize
o Homepage: <
http://www.dsv.nl/~buytenh/ext2resize/>
o Download:
<
http://www.dsv.nl/~buytenh/ext2resize/ext2resize-990617.tar.bz2>
o Author: Lennert Buytenhek <
[email protected]>.
o License: GPL
Resizes second extended filesystem.
6.16. Ext2end
o Homepage: <
http://linux.msede.com/ext2/ext2end.html>
o Maintainer: Mike Field <
[email protected]>
o License: Copyright Mike Field. To be GPLed once stable.
For use with ``LVM'' Consists of 2 utilites. ext2endable
reorganises an empty ext2 file systems to allow them to be
extended, and ext2end that extends an unmounted ext2 file system.
If ext2endable has not been run when the file system was created
ext2end will only be able to extend it to the next multiple of
256MB
6.17. Repairing/analyzing/creating Ext2 using E2fsprogs
o Homepage: <
http://web.mit.edu/tytso/www/linux/e2fsprogs.html>
o Authors:
[email protected] and
[email protected]
o Download:
<
http://sunsite.unc.edu/pub/Linux/system/Filesystems/ext2/e2fsprogs-1.06.tar.gz>
o Windows NT port: <
http://www.chat.ru/~ashedel/ext2fsnt/>
o Freshmeat: Console/Filesystems
o License: GPL
The ext2fsprogs package contains essential ext2 filesystem
utilities which consists of e2fsck, mke2fs, debugfs, dumpe2fs,
tune2fs, and most of the other core ext2 filesystem utilities.
6.18. Ext2 filesystem editor - Ext2ed
o Homepage: ?
o Author:
[email protected].
o Download:
<
http://sunsite.unc.edu/pub/Linux/system/Filesystems/ext2/ext2ed-0.1.tar.gz>
o License: GPL
EXT2ED is a disk editor for the extended2 filesystem. It will show
you the ext2 filesystem structures in a nice and intuitive way,
letting you easily "travel" between them and making the necessary
modifications.
6.19. Linux filesystem editor - lde
o Homepage: ?
o Author: Scott D. Heavner <
[email protected]>.
o Download:
<
http://sunsite.unc.edu/pub/Linux/system/Filesystems/lde-2.3.4.tar.gz>
o License: GPL
This allows you to view some Linux fs's, hex block and inode
editing are now supported and you can use it to dump an erased file
to another partition with a little bit of work. Supports ext2,
minix, and xiafs. Includes LaTeX Introduction to the Minix fs. You
must patch sources to compile on 2.2.x and 2.3.x kernels beacuse of
missing Xia header files in kernel.
6.20. Ext2 undelete utilities
o Homepage: <
http://amadeus.uprm.edu/~undelete>
o Authors: Gunther Costas, Wilfredo Lugo, Jerry Ramirez
<
[email protected]>
o Freshmeat: Console/Filesystems
o License: GPL
This is a patch for kernel 2.0.30 that adds undelete capabilities
using the "undeletable" attribute provided by the ext2fs. This
patch include man pages, the undelete daemon and utilities. Check
our web page for the latest and greatest version.
7. Macintosh Hierarchical Filesystem - HFS
All Macintosh storage devices except floppy disks are partitioned into
one or more volumes. Volumes can contain four kinds of items: files,
directories, directory threads and file threads. Each item is
described by a catalog record which is analogous to a Unix inode.
Catalog records are organized in the on-disk catalog B-Tree. Directory
contents are derived from searching the catalog B-Tree. Only a file
can occupy space outside of its catalog record.
A Macintosh "file" contains two components, or forks. The resource
fork is an indexed file containing code segments, menu items, dialog
boxes, etc. The data fork has the "stream of bytes" semantics of a
Unix file contents. Each fork is comprised of one or more extents or
contiguous runs of blocks. An extent descriptor encodes an extent's
starting block and length into a 32bit quantity. The first extent
record (three extent descriptors) of each fork is a part of the file's
catalog record. Any further extent records are kept in the extents
overflow B-Tree.
In addition to file and B-Tree extents a volume also contains two boot
blocks, a volume information block, and a free space bitmap. There is
a remarkable amount of redundancy in the on diskdata structures which
improves crash recovery. While not strictly a part of the filesystem,
it should be noted that several catalog record fields are reserved for
the exclusive use of Finder, a program which handles user access to
the filesystem and automatically maintains associations between
applications and data files. Thus, HFS must also maintain this Finder
info.
Every file and directory on an HFS volume has an identification
number, similar to an inode number in the Unix filesystem. However, a
file or directory is named by its parent's identification number and
the file or directory's file name, which is a 32 character string that
can contain nulls. This combination is the search key to the volume's
catalog B-Tree. The catalog B-Tree differs from a traditional B-Tree
structure in that all the nodes at each level of the B-Tree are linked
together to form a doubly linked list and all of the records are in
the leaf nodes. These variations permit accessing many items in the
same directory by traversing the leaves using the linked list.
Strictly speaking, the HFS B-Trees are a variant of B+-Trees although
Apple's technical documentation calls them B*-Trees.
Each directory, including the root directory, contains its directory
thread, which has the empty filename. The directory thread record
contains the name of the directory and the id of the parent of the
directory. Similarly, filethreads contain the name of a file and the
id of the directory they are in. While every directory must contain a
directory thread, file threads are very uncommon. In fact, both are
examples of HFS redundancy - for undamaged trees, threads are not
strictly necessary. Both file and directory records contain 32 bytes
of information used by Finder. The first three extent descriptors for
the catalog B-Tree are kept in the volume information block. If the
catalog B-Tree file grows beyond three extents, the remaining extent
descriptors are kept in the extents overfow.
HFS and HFS+ (also called Sequoia) filesystems are well documented.
The best source of tech. information about HFS can be found in the
Inside Mactosh series of books. Look at
<
http://developer.apple.com/techpubs/mac/Files/Files-99.html>. The
HFS+ filesystem is described in Technote 1150, available online at
<
http://developer.apple.com/technotes/tn/tn1150.html>. A lot of
information is available also in other technotes. This links are
collected by Paul H. Hargrove:
o <
http://developer.apple.com/dev/technotes/fl/fl_22.html> - HFS
Ruminations.
o <
http://developer.apple.com/dev/technotes/fl/fl_32.html> - Hey,
Buddy, Can You Spare A Block?
o <
http://developer.apple.com/dev/technotes/fl/fl_505.html> - Alias
Manager Q&As
o <
http://developer.apple.com/dev/technotes/fl/fl_515.html> - File
Manager File Handling Q&As
o <
http://developer.apple.com/dev/technotes/fl/fl_530.html> - File
Manager Volume Handling Q&As
o <
http://developer.apple.com/dev/qa/ops/ops08.html> - Bizarre
Extension Loading Order: BackQuote Sorts Between "A" and "B"
o <
http://developer.apple.com/dev/technotes/tb/tb_535.html> - Finder
Q&As
7.1. Accessing HFS from Linux
o Homepage: <
http://www-sccm.stanford.edu/~hargrove/HFS/>
o Author: Paul. Hargrove <
[email protected]>
o Freshmeat: Console/Filesystems
o License: GPL
7.2. Accessing HFS from OS/2 (HFS/2)
o Homepage: <
http://www.student.nada.kth.se/~f96-bet/HFS/>
o Author: Marcus Better <
[email protected]>
HFS/2 lets OS/2 users seamlessly read and write files on diskettes
formatted with the Hierarchical File System, the file system used by
Macintosh computers. With HFS/2, Macintosh diskettes can be used just
as if they were regular diskettes.
This program is no longer being developed, because author doesn't use
OS/2. If you are willing to maintain the program, let him know.
7.3. Accessing HFS from Windows 95/98/NT (HFV Explorer)
o Homepage: <
http://gamma.nic.fi/~lpesonen/HFVExplorer/>
o Author: Lauri Pesonen <
[email protected]>
o Access: R/W access to floppies, Zip disks and virtual volume files.
Read access to HFS and hybrid CD's.
o License: GPL
An HFS volume browser for Windows NT and Windows 9x based on
hfsutils. Launch pad support for all major Macintosh emulators
running on Windows.
7.4. Accessing HFS from DOS (MAC-ETTE)
o Homepage: ?
o Author: Paul E. Thomson
o Download: <
http://home2.inet.tele.dk/shefan/macette3.zip>
o Access: Read-Only
o License: Shareware ($34)
Mac-ette is a PC utility which can read, write, format and
duplicate Macintosh HFS format 1.4 Meg diskettes on a PC equipped
with a 3.5 inch high density diskette drive.
7.5. HFS utils
o Homepage: <
http://www.mars.org/home/rob/proj/hfs/>
o Author: Robert Leslie <
[email protected]>
o OS/2 port: <
http://www.f.kth.se/~f96-bet/hfsutils/>
The hfsutils package contains a set of command-line utilities such as
hformat, hmount, hdir, hcopy, etc. They allow read-write access of
files and directories on HFS volumes.
7.6. MacFS: A Portable Macintosh File System Library
o Tech report: <
http://reports-
archive.adm.cs.cmu.edu/anon/1998/abstracts/98-145.html>
o Author: Peter A. Dinda <
[email protected]>, George C. Necula,
and Morgan Price
o Download: <
ftp://ftp.cs.cmu.edu/user/pdinda/MacFS_0.1.tar.gz>
o Access: Read/Write, full open/read/write/seek/close support
o License: Free for noncommercial and nonmilitary use, see
<
ftp://ftp.cs.cmu.edu/user/pdinda/MacFS_0.1.LICENSE>
This is a Macintosh file system library which is portable to a
variety of operating systems and platforms. It presents a
programming interface sufficient for creating a user level API as
well as file system drivers for operating systems that support
them. Authors implemented and tested such a user level API and
utility programs based on it as well as an experimental Unix
Virtual File System. They also describe the Macintosh Hierarchical
File System and their implementation and note that the design is
not well suited to reentrancy and that its complex data structures
can lead to slow implementations in multiprogrammed environments.
Performance measurements show that our implementation is faster
than the native Macintosh implementation at creating, deleting,
reading and writing files with small request sizes, but slower than
the Berkeley Fast File System (FFS.) However, the native Macintosh
implementation can perform large read and write operations faster
that either our implementation or FFS.
8. ISO 9660 - CD-ROM filesystem
8.1. RockRidge extensions
Extensions allowing long filenames and Unix-style symbolic links.
8.2. Joliet extensions
Joliet is a Microsoft extension to the ISO 9660 filesystem that allows
Unicode characters to be used in filenames. This is a benefit when
handling internationalization. Like the Rock Ridge extensions, Joliet
also allows long filenames.
8.3. Hybrid CD-ROMs
8.4. Physical formats
8.4.1. CD-DA - Audio CDs
8.4.2. Data CDs
8.4.3. Recordable CDs
8.4.3.1. CD-MO - Magneto-optical
8.4.3.2. CD-WO - Write-once
8.4.3.3. CD-RW - Rewritable CDs
8.4.4. CD Extra - eXtended Architecture
8.4.4.1. MODE-1
8.4.4.2. MODE-2
8.4.4.2.1. FORM-1
8.4.4.2.2. FORM-2
8.4.5. Video CD
8.5. Accessing Joliet from Linux
o Homepage: <
http://bmrc.berkeley.edu/people/chaffee/joliet.html>
o License: GPL
8.6. Accessing Joliet from BeOS
o Homepage: <
http://www.iae.nl/users/gertjan/be/>
o Author: Gertjan van Ratingen <
[email protected]>
o License: ?
It is updated ISO9660 driver to be able to use a Joliet ISO9660
extensions.
8.7. Accessing Joliet from OS/2
o Download:
<
ftp://hobbes.nmsu.edu/pub/os2/system/drivers/filesys/jcdfs.zip>
o Author: IBM
o License: ?
Jcdfs.zip archive contains CDFS.IFS driver for OS/2 with Joliet
level 3 support.
8.8. Accessing Audio CD as filesystem from BeOS
o Homepage: <
http://www.xs4all.nl/~marcone/be.html>
o Download: <
http://www.xs4all.nl/~marcone/be/files/cdda5.zip>
(PPC/Intel archive)
o Author: Marco ?
o License: ?
This filesystem add-on will allow you (if your CD drive supports
it) to treat a regular audio CD as if it were a bunch of WAV files.
You can copy the files, encode them to mp3, play them slower,
faster, even backwards.
8.9. Creating Hybrid CD-ROMs (mkhybrid)
o Homepage: <
http://www.ps.ucl.ac.uk/~jcpearso/mkhfs.html>
o Download: <
ftp://ftp.ge.ucl.ac.uk/pub/mkhfs/>
o Author: <
[email protected]>
o License: ?
Make an ISO9660/HFS/JOLIET shared hybrid CD volume
9. Other filesystems
9.1. ADFS - Acorn Disc File System
The Acorn Disc Filing System is the standard filesystem of the RiscOS
operating system which runs on Acorn's ARM-based Risc PC systems and
the Acorn Archimedes range of machines.
Linux kernel 2.1.x+ supports this filesystem. Author of Linux
filesystem implementation is Russell King <
[email protected]>.
9.2. AFFS - Amiga fast filesystem
The Fast File System (FFS) is the common filesystem used on hard disks
by Amiga(tm) systems since AmigaOS Version 1.3 (34.20).
Linux kernel 2.1.x+ supports this filesystem. Author of Linux
filesystem implementation is Ray Burr <
[email protected]>.
9.3. BeFS - BeOS filesystem
BeFS is ``journaling'' filesystem used in BeOS. For more information
about BeFS see Practical File System Design with the Be File System
book or BeFS linux driver source code.
Linux BeFS implementation:
o Homepage: <
http://hp.vector.co.jp/authors/VA008030/bfs/>
o Download:
<
http://hp.vector.co.jp/authors/VA008030/bfs/bfs-19990528.tar.gz>
o Author: Makoto Kato <
[email protected]>
o Access: Read-only
o License: GPL
This driver supports x86 and PowerPC Linux platform. Also, it only
supports readable in hard disk and floppy disk.
9.4. BFS - UnixWare Boot Filesystem
UnixWare BFS filesystem type is a special-purpose filesystem. It was
designed for loading and booting UnixWare kernel. BFS was designed as
a ``contiguous filesystem''. BFS supports only one (root) directory
and you can create only regular files; no subdirs or special files
such as devices or sockets can be created.
For more information about BFS see
<
http://uw7doc.sco.com/FS_admin/_The_bfs_File_System_Type.html>.
o <
http://uw7doc.sco.com/FS_admin/_The_bfs_Superblock.html> -
superblock
o <
http://uw7doc.sco.com/FS_admin/_bfs_Inodes.html> - inodes
o <
http://uw7doc.sco.com/FS_admin/_bfs_Storage_Blocks.html> - storage
blocks
You can access BFS filesystem from Linux:
o Homepage: <
http://www.ocston.org/~tigran/patches/bfs/>
o Download: In the Linux kernel, patches available at homepage.
o Author: Tigran A. Aivazian <
[email protected]>
o License: GPL
o Access: Read/write (write part is limited, no compactification yet)
The support for BFS is included in the Linux kernel since version
2.3.25. If you are using an earlier kernel, check if BFS homepage
contains a patch which adds support for this filesystem. The
homepage also contains bugfixes/enhancement which are not yet
merged into the official kernel.
There is also mine old implementation, which is now obsolete. My plan
is to port this code to FreeBSD:
o Homepage: <
http://www.penguin.cz/~mhi/fs/bfs/>
o Download: <
ftp://ftp.penguin.cz/pub/users/mhi/bfs/>
o Author: Martin Hinner <
[email protected]>
o License: GPL
o Access: Read-only
This is read-only UnixWare Boot filesystem support for Linux. You
can use it to mount read-only your UnixWare /stand partition or
floppy disks. I don't plan a read-write version, but if you want it
mail me. You might be also interested in ``VxFS'' Linux support.
9.5. CrosStor filesystem
This is new name for High throughput filesystem (HTFS). For more
information see CrosStor homepage at <
http://www.crosstor.com>.
9.6. DTFS - Desktop filesystem
Goals in designing the Desktop File System were influenced by
impression of what environment was like for small computer systems.
DTFS compress the data stored in regular files to reduce disk space
requirements (directories remain uncompressed). Compression is
performed a page at a time and occur 'on-the-fly'. DTFS supports LZW
and no-compression but you can add your own algorithms. Some space is
saved by not pre-allocating inodes. Any disk block is fair game to be
allocated as an inode. Each inode is stored as a B+tree. For more
information see DTFS USENIX paper (you can download it from
<
ftp://ftp.crosstor.com/pub/DTFS/papers/>).
Read/Write commercial driver available from CrosStor for UnixWare and
SUN Solaris:
o Download: <
ftp://ftp.crosstor.com/pub/DTFS/>
o License: Commercial?
o Access: Read/Write
9.7. EFS - Enhanced filesystem (Linux)
The Enhanced Filing system project aims to create a new filing system
for Linux and eventually other OSs which will allow the administrator
to define mountable "file systems" on a set of block devices (either
hard drives or partitions). The aim is to allow file systems to be
added or removed from the partition set while the system is running
and partitions may be added to a set (or removed if the remaining
partitions have enough space to contain all the data) while the system
is running.The two main aims are to allow a number of mountable file
systems to share the same pool of storage space (IE have the user home
dirs on the same drive as the news spool but have separate accounting
for them), and to allow the easy addition of more hard drives to allow
more space.
Some other features that authors want to implement are
``logging/journaling'', support for as many OSs as possible (although
all work will be initially done on Linux), and quotas in the FS so we
don't need to waste ages running a silly quotacheck program at boot -
the logging should avoid quotacheck the same way it avoids fsck! They
want to be able to boot a system with 10gig of news spread over 4 hard
drives with full quotas AFTER a power failure with less than 20
seconds for mounting file systems!
Homepage of Enhanced FS is at
<
http://www.coker.com.au/~russell/enh/>. Contact Russell Coker
<
[email protected]> for more information.
9.8. EFS - Extent filesystem (IRIX)
The Extent File System (efs) is Silicon Graphics' early block-device
filesystem, widely used on pre-6.0 versions of IRIX. Since 6.0, xfs
has been bundled with IRIX and users are being encouraged to migrate
to xfs filesystems. IRIX support for efs will be read-only in versions
of IRIX beyond 6.5, however efs is still very much in use on SGI
software distribution CDs.
There are two kernel modules for linux to access EFS filesystem.
o Homepage: <
http://aeschi.ch.eu.org/efs/>
o Download: <
http://aeschi.ch.eu.org/efs/efs-1.0b.tar.gz>
o Author: Al Smith <
[email protected]>
o License: GPL
o Access: Read-only
The efs kernel module is an implementation of the extent file
system for linux 2.2 kernels. An efs implementation
(efsmod-0.6.tar.gz) was originally written for 1.x kernels by
Christian Vogelgsang. In this implementation the code has
undergone a complete rewrite and is also endian-clean. To use the
efs module, you will need to have at least a 2.2 kernel. To mount
IRIX CDs, your CD-ROM will need to be able to cope with 512-byte
blocks. This version of efs contains support for hard-disk
partitions, and also contains a kernel patch to allow you to
install the efs code into your linux kernel tree. Handling of large
files has also been vastly improved.
Original efsmod is also available:
o Homepage: <
http://wwwcip.informatik.uni-
erlangen.de/user/cnvogelg/proj.html>
o Download: <
http://wwwcip.informatik.uni-
erlangen.de/user/cnvogelg/bin/efsmod-0.6.tgz>
o Author: Christian Vogelgsang
o License: GPL
o Access: Read-only
Efs-mod 0.6 is original EFS read/only module for Linux. Version 0.6
finished but Project frozen due to lack of time and information for
implementing the write part.
9.8.1. EFS and UFS library, libfs
o Download: <
ftp://ivo.cps.unizar.es/pub/SPDsoft/libfs.tar.gz>
o Author: J.A. Gutierrez <
[email protected]>
o License: GPL
o Access: Read/Only IRIX EFS and Sun UFS
A C library to read EFS and UFS from WinNT x86, SunOS and IRIX.
Easy to use (Posix like interface) and to links aginst existent
code FTP server has also winefssh.exe and winufssh.exe, simple
WinNT binaries to interactively read UFS and EFS file systems. Not
a very polished/documented package, but somebody may find it
useful.
Useful links:
o IRIX EFS filesystem brief description:
<
http://squish.ucs.indiana.edu:80/ebt-bin/nph-
dweb/dynaweb/SGI_Admin/IA_DiskFiles/@ebt-
link;td=8?target=%25N%14_7484_START_RESTART_N%25>
9.9. FFS - BSD Fast filesystem
This is native filesystem for most BSD unixes (FreeBSD, NetBSD,
OpenBSD, Sun Solaris, ...).
See also: ``SFS, secure filesystem'', ``UFS''.
9.10. GPFS - General Parallel Filesystem
This is a UNIX(tm) operating system style file system designed for the
RS/6000 SP(tm) server. It allows applications on multiple nodes to
share file data. GPFS supports very large file systems and stripes
data across multiple disks for higher performance. GPFS is based on a
shared disk model which provides lower overhead access to disks not
directly attached to the application nodes and uses a distributed
locking protocol to provide full data coherence for access from any
node. It offers many of the standard AIX(tm) file system interfaces
allowing most applications to execute without modification or
recompiling. These capabilities are available while allowing high
speed access to the same data from all nodes of the SP system, and
providing full data coherence for operations occurring on the various
nodes. GPFS attempts to continue operation across various node and
component failures assuming that sufficient resources exist to
continue.
o <
http://www.austin.ibm.com/resource/technology/paper1.html>
9.11. HFS - HP-UX Hi performance filesystem
This is the second hfs that appears in this howto. It is used in older
HP-UX versions.
9.12. HTFS - High throughput filesystem
Useful links:
o SCO OpenServer 5 filesystems whitepaper:
<
http://www.sco.com/products/Whitepapers/family/filesy4.htm>
Read/Write commercial driver available from CrosStor:
o Download: <
ftp://ftp.crosstor.com/pub/HTFS/>
o License: Commercial?
o Access: Read/Write
9.13. JFS - Journaled filesystem (HP-UX, AIX, OS/2 5)
9.14. LFS - Linux log structured filesystem
Linux Log structured filesystem implementation called d(t)fs:
o Homepage: <
http://www.complang.tuwien.ac.at/czezatke/lfs.html>
o Author: Christian Czezatke <
[email protected]>
o License: GPL
o Access: rw/long filenames, etc
d(t)fs is a log-structured filesystem project for Linux.
Currently, the filesystem is mostly up and running, but no cleaner
has been written so far.
There will also be a dtfs mailing list that will be announced on the
homepage. For more information you can have a look at:
<
http://www.xss.co.at/mailman/listinfo.cgi/dtfs>
o <
http://collective.cpoint.net/lfs/> - The kfs Homepage Cornelius
"Kees" Cook has started a Linux Log--Structured Filesystem project
before dtfs came to live.
o <
http://lucien.blight.com/~c-cook/prof/lfs/> - Another (death) LFS
implementation ;-)
o <
http://www.eecs.harvard.edu/~margo/usenix.195/> - Margo Seltzer's
<
[email protected]> LFS page
9.15. MFS - Macintosh filesystem
MFS is original Macintosh filesystem. It has been replaced by HFS /
HFS+. If you can provide further information, mail me please.
9.16. Minix filesystem
This is Minix native filesystem. It was also used in first versions of
Linux.
9.17. NWFS - Novell NetWare filesystem
NWFS is native in Novell NetWare OS. It is modified FAT-based
filesystem. Two variants of this filesystem exists. 16bit NWFS 286 is
used in NetWare 2.x. NetWare 3.x, 4.x and 5 use 32bit NWFS 386.
9.17.1. NetWare filesystem / 286
(todo)
9.17.2. NetWare filesystem / 386
(todo)
9.17.3. Accessing NWFS-386 from Linux
o Homepage: <
http://www.timpanogas.com/html/fenris_for_linux.html>
o Download: <
ftp://207.109.151.240/nwfs/>
o Author: Timpanogas Research Group, Inc. (
[email protected])
o License: GPL
o Access: Read-Only
This driver allows you to mount NWFS-386 filesystem on Linux.
9.18. NSS - Novell Storage Services
This is a new 64bit ``journaling'' filesystem using a ``balanced
tree'' algorithms. It is used in Novell NetWare 5.
o <
http://www.novell.com/whitepapers/nw5/nss.html> - NSS Whitepaper
9.19. ODS - On Disk Structure filesystem
This is OpenVMS and VMS native filesystem.
9.20. QNX filesystem
This filesystem is used in QNX. Two major filesystem version exists,
version 2 is used by QNX 2 and version 4 by QNX 4. QNX 4 doesn't
support version 2 and vice versa.
QNX4 filesystem is now accessible from Linux 2.1.x+. Say "Y"es to 'QNX
filesystem support';
o Download: In the kernel ;)
o Author: Frank Denis <
[email protected]> (maintainer), Richard Frowijn
o License: GPL
o Access: Read (except for multi-extents files), Write (experimental)
Driver for the QNX 4 filesystem.
9.21. Reiser filesystem
Reiserfs is a file system using a variant on classical balanced tree
algorithms. The results when compared to the ext2fs conventional block
allocation based file system running under the same operating system
and employing the same buffering code suggest that these algorithms
are more effective for large files and small files not near node size
in time performance, become less effective in time performance and
more significantly effective in space performance as one approaches
files close to the node size, and become markedly more effective in
both space and time as file size decreases substantially below node
size (4k), reaching order of magnitude advantages for file sizes of
100bytes. The improvement in small file space and time performance
suggests that we may now revisit a common OS design assumption that
one should aggregate small objects using layers above the file system
layer.
Useful links:
o Reiser fs homepage <
http://devlinux.org/namesys/>
9.22. RFS (CD-ROM Filesystem)
Sony's incremental packet-writing filesystem.
9.23. RomFS - Rom filesystem
Author of Linux RomFS implemplementation is Janos Farkas
<
[email protected]> For more information see
/usr/src/linux/Documentation/filesystems/romfs.txt file.
9.24. SFS - Secure filesystem
The sfs filesystem type is a variation of the FFS filesystem type. The
boot block,superblock, storage blocks, and free blocks for the sfs
filesystem type are, at the administrative level, identical to those
for FFS. The inodes differ from FFS inodes, however. Each odd-
numbered inode is reserved for security information. The information
contains Access Control List information. I'm not sure if SFS has any
other abilities though.
SFS links:
o <
http://uw7doc.sco.com/FS_admin/_The_sfs_File_System_Type.html> -
UnixWare 7 documentation: SFS Filesystem
9.25. Spiralog filesystem (OpenVMS)
Spiralog is a 64bit high-performance filesystem for the OpenVMS. The
Spiralog combines ``log-structured'' technology with more traditional
``B-tree'' technology to provide a general abstraction. The B-tree
mapping mechanism uses write-ahead logging to give stability and
recoverability guarantees.
Spiralog-related links at Digital:
o <
http://www.digital.com/info/SP6048/> - Spiralog File System for
OpenVMS Alpha
o <
http://www.digital.com/DTJM01/DTJM01AH.HTM> - Overview of the
Spiralog File System
o <
http://www.digital.com/DTJM02/DTJM02HM.HTM> - Design of the Server
for the Spiralog File System
9.26. System V and derived filesystems
Homepage of System V Linux project is at
<
http://www.knm.org.pl/prezes/sysv.html>. Maintainer of this project
is <
[email protected]>.
9.26.1. AFS - Acer Fast Filesystem
The Acer Fast Filesystem is used on SCO Open Server. It is similar to
the System V Release 4 filesystem, but it is using bitmaps instead of
chained free-list of blocks.
9.26.2. EAFS - Extended Acer Fast Filesystem
The AFS filesystem can be 'extended' to handle file names up to 255
characters, but directories entries still have 14-char names. This
filesystem type is used on SCO Open Server.
9.26.3. Coherent filesystem
9.26.4. S5
This filesystem is used in UnixWare. It's probably SystemV compatible,
but I haven't verified it yet. For more information see
<
http://uw7doc.sco.com/FS_admin/_The_s5_File_System_Type.html>.
9.26.5. S51K - SystemV 1K
9.26.6. Version 7 filesystem
This filesystem type is used on Version 7 Unix for PDP-11 machines.
9.26.7. Xenix filesystem
9.27. Text - (Philips' CD-ROM Filesystem)
Philips' standard for encoding disc and track data on audio CDs.
9.28. UDF - Universal Disk Format (DVD-ROM filesystem)
There is a Linux UDF filesystem driver:
o Homepage: <
http://trylinux.com/projects/udf/>
o Download: <
http://trylinux.com/projects/udf/udf-0.8.0.1.tar.gz>
o Author: Dave Boynton <
[email protected]>
o Mailing-list: <
[email protected]>
o License: GPL
o Access: Read-only
9.29. UFS
Note: People often call ``BSD Fast Filesystem'' incorrectly UFS. FFS
and UFS are *diferrent* filesystems. All modern Unixes use FFS
filesystem.
Useful links:
o <
http://www.sun.ca/white-papers/ufs-cluster.html> - Implementation
of write-clustering for Sun's UFS
See also: ``BSD FFS''
9.30. VxFS - Veritas filesystem (HP-UX, SCO UnixWare, Solaris)
This is commercial filesystem developer by Veritas Inc. You can see it
in HP-UX, SCO UnixWare, Solaris and probably other systems. It has
very interesting features: Extent based allocation, Journaling, access
control lists (ACLs), up to 2 terabyte large file support, online
backup (snapshot filesystem), BSD style quotas and many more.
Three VxFS versions are available with VxFS:
Version 1: This is original VxFS, not commonly in use.
Version 2: Support for filesets and dynamic inode allocation.
Version 4: Latest version, supports large files and quotas.
Note that HP-UX, Solaris and UnixWare versions use slightly different
structures, so you may not be able to read VxFS when you connect it to
different system.
VxFS related links:
o <
http://www.veritas.com/> - Veritas Inc <
[email protected]>.
o <
http://uw7doc.sco.com/ODM_FSadmin/CONTENTS.html> - VxFS ODM FS
Admin - UnixWare 7 (documentation, really good).
o <
http://uw7doc.sco.com/FS_manager/fsD.vxfsopt.html> - VxFS FS
Manager - UnixWare 7 (documentation).
o <
http://manuals.mchp.siemens.de:80/dynaweb/english/ru544e/drlugueb/o25636e1/@Generic__BookView/1641;cd=3>
- VxFS - Reliant Unix.
See also: ``VxVM (Veritas volume manager)'' and ``journaling
filesystems''.
9.30.1. VxTools
Unix command-line utilities for accessing VxFS versions 2 and 4 are
available under the GNU GPL:
o Homepage: <
http://www.penguin.cz/~mhi/fs/vxfs/>
o Download: <
ftp://ftp.penguin.cz/pub/users/mhi/vxfs/>
o Author: Martin Hinner <
[email protected]>
o Mailing-list: <
[email protected]>
o License: GPL
o Access: Read-only, command-line utilites
Vxtools is a set of command-line utilites which allow you to access
your VxFS filesystem from Linux (and possibly other Unixes).
Current version can read VxFS versions 2 and 4.
I (mhi) plan also VxFS Linux kernel driver.
AFAIK Rodney Ramdas <
[email protected]> works on VxFS driver for
FreeBSD. I don't know current status of his project, so if you want
more info contact him directly.
9.31. XFS - Extended filesystem (IRIX)
XFS(tm) is the next-generation file system for Silicon Graphics[TM]
systems, from desktop workstations to supercomputers. XFS provides
full 64-bit file capabilities that scale easily to handle extremely
large files and file systems that grow to 1 terabyte. The XFS file
system integrates volume management, guaranteed rate I/O, and
``journaling'' technology for fast, reliable recovery. File systems
can be backed up while still in use, significantly reducing
administrative overhead.
XFS is designed for a very high performance; sustained throughput in
excess of 300MB per second has been demonstrated on CHALLENGE systems.
The XFS file system scales in performance to match the CHALLENGE MP
architecture. Traditional files, directories, and file systems have
reduced performance as they grow in size. With the XFS file system,
there is no performance penalty. For example, XFS directories have
been tested with up to 32 million files in a single directory.
XFS is a journalled file system. It logs changes to the inodes,
directories and bitmaps to the disk before the original entries are
updated. Should the system crash before the updates are done they can
be recreated using the log and updated as intended.
XFS uses a space manager to allocate disk space for the file system
and control the inodes. It uses a namespace manager to control
allocation of directory files. These managers use B-tree indexing to
store file location information, significantly decreasing the access
time needed to retrieve file information.
Inodes are created as needed and are not restricted to a particular
area on a disk partition. XFS tries to position the inodes close to
the files and directories they reference. Very small files, such as
symbolic links and some directories, are stored as part of the inode,
to increase performance and save space. Large directories use B-tree
indexing within the directory file to speed up directory searches,
additions and deletions.
Useful XFS links:
o <
http://www.sgi.com/Technology/xfs-whitepaper.html> XFS whitepaper
XFS Linux port covered by the GNU General Public License is available
from SGI Inc.:
o Homepage: <
http://oss.sgi.com/projects/xfs/>
o Download: <
ftp://oss.sgi.com/www/projects/xfs/download/>
o Author: SGI Inc., <
http://www.sgi.com/>
o License: GPL
o Access: Read-write
9.32. Xia FS
This filesystem was developed to replace old Minix filesystem in
Linux. Author of this fs is Franx Xia <
[email protected]>
10. Raw partitions
11. Appendix
11.1. Network filesystems
This HOWTO is not about Network filesystems, but I should mention
them.
There is a brief list of some which I know:
11.1.1. AFS - Andrew Filesystem
o The AFS FAQ is at <
http://www.angelfire.com/hi/plutonic/afs-
faq.html>.
o Commercial clients and servers for almost all platforms (except
win98) are available from IBM. See
<
http://www.transarc.com/Product/EFS/AFS/index.html>
o A free client for Unix is available from the Arla Team at
<
http://www.stacken.kth.se/projekt/arla/>.
o A free Server is also in preparation, but not in production yet.
11.1.2. CODA
11.1.3. NFS - Network filesystem (Unix)
11.1.4. NCP - NetWare Core Protocol (Novell NetWare)
11.1.5. SMB - Session Message Block (Windows 3.x/9x/NT)
This protocol is used in Windows world.
11.2. Encrypted filesystems
11.2.1. CFS
o Homepage: ?
o Download: ?
o Author: Matt Blaze <
[email protected]>.
o License: ?
o Access: Read/Write, using DES/3DES.
CFS pushes encryption services into the Unix(tm) file system. It
supports secure storage at the system level through a standard Unix
file system interface to encrypted files. Users associate a
cryptographic key with the directories they wish to protect. Files
in these directories (as well as their pathname components) are
transparently encrypted and decrypted with the specified key
without further user intervention; cleartext is never stored on a
disk or sent to a remote file server. CFS employs a novel
combination of DES stream and codebook cipher modes to provide high
security with good performance on a modern workstation. CFS can
use any available file system for its underlying storage without
modification, including remote file servers such as NFS. System
management functions, such as file backup, work in a normal manner
and without knowledge of the key.
11.2.2. TCFS
o Homepage: <
http://tcfs.dia.unisa.it/>
o Download: <
ftp://tcfs.dia.unisa.it/pub/tcfs/>
o Authors: Luigi Catuogno <
[email protected]>, Aniello Del
Sorbo <
[email protected]>, Luigi Della Monica
<
[email protected]>, G.Cattaneo <
[email protected]>,
G.Persiano ( <
http://www.dia.unisa.it/~giuper/>), Ermelindo (Erry)
Mauriello <
[email protected]>, Angelo Celentano
<
[email protected]>, Andrea Cozzolino
<
[email protected]>.
o License: GPL
o Access: Read/Write transparently using CBC-
DES/3DES/RC5/IDEA/Others..
The main difference between TCFS and CFS is the trasparency to user
obtained by using TCFS. As a matter of fact, CFS works in user
space while TCFS works in the kernel space thus resulting in
improved performances and security. The dynamic encryption module
feature of TCFS allows a user to specify the encryption engine of
his/her choiche to be used by TCFS. Currently available only for
Linux, TCFS will be relased soon also for NetBSD, and will support
in a near future also other FS then NFS.
11.2.3. SFS
( TODO: <
http://www.cs.auckland.ac.nz/~pgut001/sfs/index.html> )
11.2.4. VS3FS: Steganographic File System for Linux
o Homepage: <
http://www.linux-security.org/sfs/>
o License: ?
o Access: ?
fspatch is a kernel patch which introduces module support for the
steganographic file system (formerly known as vs3fs, an
experimental type of filesytem that not only encrypts all
information on the disk, but also tries to hide that information in
such a way that it cannot be proven to even exist on the disk. This
enables you to keep sensitive information on a disk, while not be
prone to being forced to reveal that information. Even under
extreme circumstances, fake documents could be stored on other
parts of the disk, for which a pasword may be revealed. It should
not be possible to find out whether any other information is stored
on the disk.
11.3. Writing your own filesystem driver
11.3.1. DOS
I haven't seen yet any good page about writing DOS filesystem drivers
(Network redirectors) on the net. The best source is Ralf Brown's
interrupt list and ``iHPFS'' source code.
11.3.2. OS/2
o <
ftp://ftp.leo.org/pub/comp/os/os2/leo/devtools/doc/ifsinf.zip>
o <
ftp://hobbes.nmsu.edu/pub/os2/system/drivers/filesys/32drv170.zip>
- 32 bits OS/2 device driver and IFS support. Provides 32 bits
kernel services (DevHelp) and utility functions to 32 bits OS/2
ring 0 code (device drivers and installable file system drivers).
11.3.3. Windows NT
For more information about writing FS drivers for Windows NT see
<
http://www.ing.umu.se/~bosse/> by <
[email protected]>.
11.4. Related documents
o <
http://www.honeycomb.net/os/holistic/connect/filesys.htm> - good
page about filesystems
o <
http://home.att.net/~artnaseef/> - Linux overlay filesystem by
<
[email protected]>.
o <
http://www.braysystems.com/linux/trustees.html> - Linux trustees
o <
http://tcfs.dia.unisa.it> - Transparent Cryptography Filesystem
o <
http://www.sas.com/standards/large.file> - Large file summit -
attacks the problem of 2gig+ of file in a 32bit computer
o <
http://www.coda.cs.cmu.edu/> - The CODA project (a distributed
file system based on AFS)
o <
ftp://ftp.scis.org/pub/lfs/> - LFS related papers
o <
http://www.redhat.com:8080/HyperNews/get/khg.html> - Linux Kernel
Hacker's guide
o <
http://www.win.tue.nl/~aeb/linux/largedisk.html> - Large disk
HOWTO
o <
http://www.atnf.csiro.au/~rgooch/linux/kernel-patches.html> - The
Linux devfs
o <
http://gfs.lcse.umn.edu/> - The Global File System (GFS)
o <
ftp://hobbes.nmsu.edu/pub/os2/system/drivers/filesys/tvfs211.zip>
- The Toronto Virtual Filesystem/2.
o <
ftp://hobbes.nmsu.edu/pub/os2/system/drivers/filesys/ramfs64.zip>
Dynamic RAM drive IFS driver for OS/2
o <
http://doc.sco.com/> - UnixWare and SCO Unix documentation online
o <
http://uw7doc.sco.com/> - UnixWare 7 documentation online
o <
http://publib.boulder.ibm.com/cgi-
bin/bookmgr/BOOKS/SG244428/CCONTENTS> - Inside OS/2 LAN Server 4.0
o <
ftp://tsx-11.mit.edu/pub/linux/ALPHA/userfs/> - Linux UserFS, it
allows you to write a Linux process which implements a filesystem.
o <
http://www.nyx.net/~sgjoen/disk.html> - Stein Gjoen's Multi Disk
System Tuning HOWTO.
o <
http://linuxtoday.com/stories/5556.html> - Linux Today: Kragen's
Amazing List of Filesystems.
o <
http://www.koehntopp.de/kris/artikel/dateisysteme/> - Kristian
Kohntopp's Unix Filesystems (in German).
