Ext4 Filesystem
===============
-This is a development version of the ext4 filesystem, an advanced level
-of the ext3 filesystem which incorporates scalability and reliability
-enhancements for supporting large filesystems (64 bit) in keeping with
-increasing disk capacities and state-of-the-art feature requirements.
+Ext4 is an an advanced level of the ext3 filesystem which incorporates
+scalability and reliability enhancements for supporting large filesystems
+(64 bit) in keeping with increasing disk capacities and state-of-the-art
+feature requirements.
-Mailing list: linux-ext4@vger.kernel.org
+Mailing list: linux-ext4@vger.kernel.org
+Web site: http://ext4.wiki.kernel.org
1. Quick usage instructions:
===========================
+Note: More extensive information for getting started with ext4 can be
+ found at the ext4 wiki site at the URL:
+ http://ext4.wiki.kernel.org/index.php/Ext4_Howto
+
- Compile and install the latest version of e2fsprogs (as of this
- writing version 1.41) from:
+ writing version 1.41.3) from:
http://sourceforge.net/project/showfiles.php?group_id=2406
git://git.kernel.org/pub/scm/fs/ext2/e2fsprogs.git
- - Create a new filesystem using the ext4dev filesystem type:
+ - Note that it is highly important to install the mke2fs.conf file
+ that comes with the e2fsprogs 1.41.x sources in /etc/mke2fs.conf. If
+ you have edited the /etc/mke2fs.conf file installed on your system,
+ you will need to merge your changes with the version from e2fsprogs
+ 1.41.x.
+
+ - Create a new filesystem using the ext4 filesystem type:
- # mke2fs -t ext4dev /dev/hda1
+ # mke2fs -t ext4 /dev/hda1
- Or configure an existing ext3 filesystem to support extents and set
- the test_fs flag to indicate that it's ok for an in-development
- filesystem to touch this filesystem:
+ Or to configure an existing ext3 filesystem to support extents:
- # tune2fs -O extents -E test_fs /dev/hda1
+ # tune2fs -O extents /dev/hda1
If the filesystem was created with 128 byte inodes, it can be
converted to use 256 byte for greater efficiency via:
# tune2fs -I 256 /dev/hda1
- (Note: we currently do not have tools to convert an ext4dev
+ (Note: we currently do not have tools to convert an ext4
filesystem back to ext3; so please do not do try this on production
filesystems.)
- Mounting:
- # mount -t ext4dev /dev/hda1 /wherever
+ # mount -t ext4 /dev/hda1 /wherever
- When comparing performance with other filesystems, remember that
ext3/4 by default offers higher data integrity guarantees than most.
The big performance win will come with mballoc, delalloc and flex_bg
grouping of bitmaps and inode tables. Some test results available here:
- - http://www.bullopensource.org/ext4/20080530/ffsb-write-2.6.26-rc2.html
- - http://www.bullopensource.org/ext4/20080530/ffsb-readwrite-2.6.26-rc2.html
+ - http://www.bullopensource.org/ext4/20080818-ffsb/ffsb-write-2.6.27-rc1.html
+ - http://www.bullopensource.org/ext4/20080818-ffsb/ffsb-readwrite-2.6.27-rc1.html
3. Options
==========
your disks are battery-backed in one way or another,
disabling barriers may safely improve performance.
+inode_readahead=n This tuning parameter controls the maximum
+ number of inode table blocks that ext4's inode
+ table readahead algorithm will pre-read into
+ the buffer cache. The default value is 32 blocks.
+
orlov (*) This enables the new Orlov block allocator. It is
enabled by default.
bsddf (*) Make 'df' act like BSD.
minixdf Make 'df' act like Minix.
-check=none Don't do extra checking of bitmaps on mount.
-nocheck
-
debug Extra debugging information is sent to syslog.
errors=remount-ro(*) Remount the filesystem read-only on an error.
errors=continue Keep going on a filesystem error.
errors=panic Panic and halt the machine if an error occurs.
+data_err=ignore(*) Just print an error message if an error occurs
+ in a file data buffer in ordered mode.
+data_err=abort Abort the journal if an error occurs in a file
+ data buffer in ordered mode.
+
grpid Give objects the same group ID as their creator.
bsdgroups
"nobh" option tries to avoid associating buffer
heads (supported only for "writeback" mode).
-mballoc (*) Use the multiple block allocator for block allocation
-nomballoc disabled multiple block allocator for block allocation.
stripe=n Number of filesystem blocks that mballoc will try
to use for allocation size and alignment. For RAID5/6
systems this should be the number of data
delalloc (*) Deferring block allocation until write-out time.
nodelalloc Disable delayed allocation. Blocks are allocation
when data is copied from user to page cache.
+
Data Mode
=========
There are 3 different data modes:
projects / linux-2.6-omap-h63xx.git / blobdiff