[PATCH] Docs update: small spelling, formating etc fixes for filesystems/ext3.txt
Spelling fixes, formating changes and corrections for Documentation/filesystems/ext3.txt Signed-off-by: Jesper Juhl <jesper.juhl@gmail.com> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
This commit is contained in:
parent
c594a50db4
commit
c63ca3c8b0
Documentation/filesystems
|
@ -2,11 +2,11 @@
|
|||
Ext3 Filesystem
|
||||
===============
|
||||
|
||||
ext3 was originally released in September 1999. Written by Stephen Tweedie
|
||||
for 2.2 branch, and ported to 2.4 kernels by Peter Braam, Andreas Dilger,
|
||||
Ext3 was originally released in September 1999. Written by Stephen Tweedie
|
||||
for the 2.2 branch, and ported to 2.4 kernels by Peter Braam, Andreas Dilger,
|
||||
Andrew Morton, Alexander Viro, Ted Ts'o and Stephen Tweedie.
|
||||
|
||||
ext3 is ext2 filesystem enhanced with journalling capabilities.
|
||||
Ext3 is the ext2 filesystem enhanced with journalling capabilities.
|
||||
|
||||
Options
|
||||
=======
|
||||
|
@ -14,69 +14,71 @@ Options
|
|||
When mounting an ext3 filesystem, the following option are accepted:
|
||||
(*) == default
|
||||
|
||||
jounal=update Update the ext3 file system's journal to the
|
||||
current format.
|
||||
journal=update Update the ext3 file system's journal to the current
|
||||
format.
|
||||
|
||||
journal=inum When a journal already exists, this option is
|
||||
ignored. Otherwise, it specifies the number of
|
||||
the inode which will represent the ext3 file
|
||||
system's journal file.
|
||||
journal=inum When a journal already exists, this option is ignored.
|
||||
Otherwise, it specifies the number of the inode which
|
||||
will represent the ext3 file system's journal file.
|
||||
|
||||
journal_dev=devnum When the external journal device's major/minor numbers
|
||||
have changed, this option allows to specify the new
|
||||
journal location. The journal device is identified
|
||||
through its new major/minor numbers encoded in devnum.
|
||||
have changed, this option allows the user to specify
|
||||
the new journal location. The journal device is
|
||||
identified through its new major/minor numbers encoded
|
||||
in devnum.
|
||||
|
||||
noload Don't load the journal on mounting.
|
||||
|
||||
data=journal All data are committed into the journal prior
|
||||
to being written into the main file system.
|
||||
data=journal All data are committed into the journal prior to being
|
||||
written into the main file system.
|
||||
|
||||
data=ordered (*) All data are forced directly out to the main file
|
||||
system prior to its metadata being committed to
|
||||
the journal.
|
||||
system prior to its metadata being committed to the
|
||||
journal.
|
||||
|
||||
data=writeback Data ordering is not preserved, data may be
|
||||
written into the main file system after its
|
||||
metadata has been committed to the journal.
|
||||
data=writeback Data ordering is not preserved, data may be written
|
||||
into the main file system after its metadata has been
|
||||
committed to the journal.
|
||||
|
||||
commit=nrsec (*) Ext3 can be told to sync all its data and metadata
|
||||
every 'nrsec' seconds. The default value is 5 seconds.
|
||||
This means that if you lose your power, you will lose,
|
||||
as much, the latest 5 seconds of work (your filesystem
|
||||
will not be damaged though, thanks to journaling). This
|
||||
default value (or any low value) will hurt performance,
|
||||
but it's good for data-safety. Setting it to 0 will
|
||||
have the same effect than leaving the default 5 sec.
|
||||
This means that if you lose your power, you will lose
|
||||
as much as the latest 5 seconds of work (your
|
||||
filesystem will not be damaged though, thanks to the
|
||||
journaling). This default value (or any low value)
|
||||
will hurt performance, but it's good for data-safety.
|
||||
Setting it to 0 will have the same effect as leaving
|
||||
it at the default (5 seconds).
|
||||
Setting it to very large values will improve
|
||||
performance.
|
||||
|
||||
barrier=1 This enables/disables barriers. barrier=0 disables it,
|
||||
barrier=1 enables it.
|
||||
barrier=1 This enables/disables barriers. barrier=0 disables
|
||||
it, barrier=1 enables it.
|
||||
|
||||
orlov (*) This enables the new Orlov block allocator. It's enabled
|
||||
by default.
|
||||
orlov (*) This enables the new Orlov block allocator. It is
|
||||
enabled by default.
|
||||
|
||||
oldalloc This disables the Orlov block allocator and enables the
|
||||
old block allocator. Orlov should have better performance,
|
||||
we'd like to get some feedback if it's the contrary for
|
||||
you.
|
||||
oldalloc This disables the Orlov block allocator and enables
|
||||
the old block allocator. Orlov should have better
|
||||
performance - we'd like to get some feedback if it's
|
||||
the contrary for you.
|
||||
|
||||
user_xattr Enables Extended User Attributes. Additionally, you need
|
||||
to have extended attribute support enabled in the kernel
|
||||
configuration (CONFIG_EXT3_FS_XATTR). See the attr(5)
|
||||
manual page and http://acl.bestbits.at to learn more
|
||||
about extended attributes.
|
||||
user_xattr Enables Extended User Attributes. Additionally, you
|
||||
need to have extended attribute support enabled in the
|
||||
kernel configuration (CONFIG_EXT3_FS_XATTR). See the
|
||||
attr(5) manual page and http://acl.bestbits.at/ to
|
||||
learn more about extended attributes.
|
||||
|
||||
nouser_xattr Disables Extended User Attributes.
|
||||
|
||||
acl Enables POSIX Access Control Lists support. Additionally,
|
||||
you need to have ACL support enabled in the kernel
|
||||
configuration (CONFIG_EXT3_FS_POSIX_ACL). See the acl(5)
|
||||
manual page and http://acl.bestbits.at for more
|
||||
information.
|
||||
acl Enables POSIX Access Control Lists support.
|
||||
Additionally, you need to have ACL support enabled in
|
||||
the kernel configuration (CONFIG_EXT3_FS_POSIX_ACL).
|
||||
See the acl(5) manual page and http://acl.bestbits.at/
|
||||
for more information.
|
||||
|
||||
noacl This option disables POSIX Access Control List support.
|
||||
noacl This option disables POSIX Access Control List
|
||||
support.
|
||||
|
||||
reservation
|
||||
|
||||
|
@ -88,7 +90,7 @@ bsddf (*) Make 'df' act like BSD.
|
|||
minixdf Make 'df' act like Minix.
|
||||
|
||||
check=none Don't do extra checking of bitmaps on mount.
|
||||
nocheck
|
||||
nocheck
|
||||
|
||||
debug Extra debugging information is sent to syslog.
|
||||
|
||||
|
@ -97,7 +99,7 @@ errors=continue Keep going on a filesystem error.
|
|||
errors=panic Panic and halt the machine if an error occurs.
|
||||
|
||||
grpid Give objects the same group ID as their creator.
|
||||
bsdgroups
|
||||
bsdgroups
|
||||
|
||||
nogrpid (*) New objects have the group ID of their creator.
|
||||
sysvgroups
|
||||
|
@ -108,81 +110,81 @@ resuid=n The user ID which may use the reserved blocks.
|
|||
|
||||
sb=n Use alternate superblock at this location.
|
||||
|
||||
quota Quota options are currently silently ignored.
|
||||
noquota (see fs/ext3/super.c, line 594)
|
||||
quota
|
||||
noquota
|
||||
grpquota
|
||||
usrquota
|
||||
|
||||
|
||||
Specification
|
||||
=============
|
||||
ext3 shares all disk implementation with ext2 filesystem, and add
|
||||
transactions capabilities to ext2. Journaling is done by the
|
||||
Journaling block device layer.
|
||||
Ext3 shares all disk implementation with the ext2 filesystem, and adds
|
||||
transactions capabilities to ext2. Journaling is done by the Journaling Block
|
||||
Device layer.
|
||||
|
||||
Journaling Block Device layer
|
||||
-----------------------------
|
||||
The Journaling Block Device layer (JBD) isn't ext3 specific. It was
|
||||
design to add journaling capabilities on a block device. The ext3
|
||||
filesystem code will inform the JBD of modifications it is performing
|
||||
(Call a transaction). the journal support the transactions start and
|
||||
stop, and in case of crash, the journal can replayed the transactions
|
||||
to put the partition on a consistent state fastly.
|
||||
The Journaling Block Device layer (JBD) isn't ext3 specific. It was design to
|
||||
add journaling capabilities on a block device. The ext3 filesystem code will
|
||||
inform the JBD of modifications it is performing (called a transaction). The
|
||||
journal supports the transactions start and stop, and in case of crash, the
|
||||
journal can replayed the transactions to put the partition back in a
|
||||
consistent state fast.
|
||||
|
||||
handles represent a single atomic update to a filesystem. JBD can
|
||||
handle external journal on a block device.
|
||||
Handles represent a single atomic update to a filesystem. JBD can handle an
|
||||
external journal on a block device.
|
||||
|
||||
Data Mode
|
||||
---------
|
||||
There's 3 different data modes:
|
||||
There are 3 different data modes:
|
||||
|
||||
* writeback mode
|
||||
In data=writeback mode, ext3 does not journal data at all. This mode
|
||||
provides a similar level of journaling as XFS, JFS, and ReiserFS in its
|
||||
default mode - metadata journaling. A crash+recovery can cause
|
||||
incorrect data to appear in files which were written shortly before the
|
||||
crash. This mode will typically provide the best ext3 performance.
|
||||
In data=writeback mode, ext3 does not journal data at all. This mode provides
|
||||
a similar level of journaling as that of XFS, JFS, and ReiserFS in its default
|
||||
mode - metadata journaling. A crash+recovery can cause incorrect data to
|
||||
appear in files which were written shortly before the crash. This mode will
|
||||
typically provide the best ext3 performance.
|
||||
|
||||
* ordered mode
|
||||
In data=ordered mode, ext3 only officially journals metadata, but it
|
||||
logically groups metadata and data blocks into a single unit called a
|
||||
transaction. When it's time to write the new metadata out to disk, the
|
||||
associated data blocks are written first. In general, this mode
|
||||
perform slightly slower than writeback but significantly faster than
|
||||
journal mode.
|
||||
In data=ordered mode, ext3 only officially journals metadata, but it logically
|
||||
groups metadata and data blocks into a single unit called a transaction. When
|
||||
it's time to write the new metadata out to disk, the associated data blocks
|
||||
are written first. In general, this mode performs slightly slower than
|
||||
writeback but significantly faster than journal mode.
|
||||
|
||||
* journal mode
|
||||
data=journal mode provides full data and metadata journaling. All new
|
||||
data is written to the journal first, and then to its final location.
|
||||
In the event of a crash, the journal can be replayed, bringing both
|
||||
data and metadata into a consistent state. This mode is the slowest
|
||||
except when data needs to be read from and written to disk at the same
|
||||
time where it outperform all others mode.
|
||||
data=journal mode provides full data and metadata journaling. All new data is
|
||||
written to the journal first, and then to its final location.
|
||||
In the event of a crash, the journal can be replayed, bringing both data and
|
||||
metadata into a consistent state. This mode is the slowest except when data
|
||||
needs to be read from and written to disk at the same time where it
|
||||
outperforms all others modes.
|
||||
|
||||
Compatibility
|
||||
-------------
|
||||
|
||||
Ext2 partitions can be easily convert to ext3, with `tune2fs -j <dev>`.
|
||||
Ext3 is fully compatible with Ext2. Ext3 partitions can easily be
|
||||
mounted as Ext2.
|
||||
Ext3 is fully compatible with Ext2. Ext3 partitions can easily be mounted as
|
||||
Ext2.
|
||||
|
||||
|
||||
External Tools
|
||||
==============
|
||||
see manual pages to know more.
|
||||
See manual pages to learn more.
|
||||
|
||||
tune2fs: create a ext3 journal on a ext2 partition with the -j flag.
|
||||
mke2fs: create a ext3 partition with the -j flag.
|
||||
debugfs: ext2 and ext3 file system debugger.
|
||||
|
||||
tune2fs: create a ext3 journal on a ext2 partition with the -j flags
|
||||
mke2fs: create a ext3 partition with the -j flags
|
||||
debugfs: ext2 and ext3 file system debugger
|
||||
|
||||
References
|
||||
==========
|
||||
|
||||
kernel source: file:/usr/src/linux/fs/ext3
|
||||
file:/usr/src/linux/fs/jbd
|
||||
kernel source: <file:fs/ext3/>
|
||||
<file:fs/jbd/>
|
||||
|
||||
programs: http://e2fsprogs.sourceforge.net
|
||||
programs: http://e2fsprogs.sourceforge.net/
|
||||
|
||||
useful link:
|
||||
http://www.zip.com.au/~akpm/linux/ext3/ext3-usage.html
|
||||
useful links: http://www.zip.com.au/~akpm/linux/ext3/ext3-usage.html
|
||||
http://www-106.ibm.com/developerworks/linux/library/l-fs7/
|
||||
http://www-106.ibm.com/developerworks/linux/library/l-fs8/
|
||||
|
|
Loading…
Reference in New Issue