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The fourth extended filesystem (ext4) is now a fully supported feature in Red Hat Enterprise Linux 5.6. ext4 is based on the third extended filesystem (ext3) and features a number of improvements, including: support for larger file sizes and offsets, faster and more efficient allocation of disk space, no limit on the number of subdirectories within a directory, faster file system checking, and more robust journaling.
Please note that "e4fsprogs" simply contains renamed static binaries from the
equivalent upstream e2fsprogs release; it is packaged this way for Red Hat
Enterprise Linux 5 to ensure that the many changes
included for ext4 do not destabilize the core e2fsprogs in RHEL5."
To use it, update to 5.6 or later, boot into 2.6.18-128.el5 or higher, and yum install e4fsprogs.
To complement the addition of ext4 as a fully supported filesystem in Red Hat Enterprise Linux 5.6, the e4fsprogs package has been updated to the latest upstream version. e4fsprogs contains utilities to create, modify, verify, and correct the ext4 filesystem.
In previous Red Hat Enterprise Linux 5 releases, the ext4 filesystem was a Technology Preview feature and might have been known by the release name, ext4dev.
The e4fsprogs packages contain a number of utilities for creating, checking, modifying, and correcting inconsistencies in fourth extended (ext4 and ext4dev) file systems. e4fsprogs contains
This update fixes the following bug:
* Previously, the resize4fs utility mishandled the resizing of an ext4 file system
to a smaller size. As a consequence, files containing many extents could become
corrupted if they were moved during the resize process. With this update, resize4fs
now maintains a consistent extent tree when moving files containing
many extents, and such files no longer become corrupted in this scenario. (BZ#1033548)
Users of e4fsprogs are advised to upgrade to these updated packages, which fix this bug.
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June 20, 2013
As a part of mke2fs's option parsing cleanup, the use of the -R option will give a warning that it is deprecated (it has been so documented since 2005) and -E should be used instead.
Mke2fs will not give warnings about the bigalloc and quota options in quiet mode.
If an invalid journal size is given to mke2fs, it will now complain and exit sooner.
Debugfs was erroneously giving spurious error messages for certain extent_inode subcommands which take arguments (split_node, replace_node, and insert_node). This has been fixed.
Fix the parsing of the 's' (sectors) in parse_num_blocks2, which among other programs is used by mke2fs.
Change mke2fs so that it does not set the root directory to the real uid/gid of the mke2fs process. Add the extended option root_owner to override this behavior.
Fix resize2fs when shrinking file systems to make sure that bitmap blocks aren't left outside the bounds of the shrunken file system. This could happen with flex_bg file systems that were grown using the old online resizing algorithm.
E2fsck will now detect and repair corrupted extent trees which contain invalid extents at the end of the extent tree leaf block.
E2fsck will now longer complain about zero length extended attribute values.
Fix a regression introduced in e2fsprogs v1.42 which caused e2image -s to crash.
Add safety check so tune2fs will not attempt to set the inode size to be larger than the block size.
Fix e2fsck so it can check a read-only root file system with an external journal. (Addresses Debian Bug: #707030
Fix off-line resizing of file systems with flex_bg && !resize_inode (Addresses Debian Bug: #696746)
Fix e2image with large (> 32-bit) file systems (Addresses Debian Bug: #703067)
Enhance chattr to allow clearing the extent flag if the kernel allows migrating extent based files to use indirect blocks.
On Thu, Feb 19, 2009 at 11:48:38PM +0100, J.A. Magallón wrote:
> - Where is the 'official' source for e4defrag ?
> - I've read that e4defrag needs in-kernel support.
> Is it already in mainline ?
> From what kernel version ?
Ext4's defragmentation code is still under development. There are
multiple versions of e4defrag, paired with kernel patches that have
been submitted to linux-ext4@xxxxxxxxxxxxxxxx The patches are not yet
in in mainline, and the kernel/userspace interface is still subject to
change (which is why it's not in mainline yet).
> - I have seen that some distros refer to a package called 'e4fsprogs'.
> Does that thing exist ? Where ?
e4fsprogs was a snapshot of something between e2fprogs 1.41.1 and
e2fsprogs 1.41.2, if I remember correctly, and it was created for
RHEL5's technology preview of ext4; the concern was that Red Hat
didn't want to risk making a major change to e2fsprogs in an
enterprise distribution; so e4fsprogs is the e2fsprogs's various
binaries with ext4 support, statically linked.
> - Booting:
> - There seem to be patches for grub
> to boot ext4
> - and a Google SoC called 'grub4ext4'.
> -and there is also grub2 (ext4 support in svn).
> What would you recommend ?
I can't speak to that; I'm still using an ext3 boot partition since
until very recently I was still using an somewhat oldish (Ubuntu
Hardy) userspace. It's exciting enough to be on the bleeding edge of
the kernel, I don't need to be on the bleeding edge of userspace too. :-)
(For example, after my laptop got stolen and I decided to finally move
to Ubuntu Intrepid, with pulseaudio sound is only sporadically
working. And I don't have time to debug how and why the new
complexities in the !@#!@ sound system is failing. I'll probably have
to carve out a few hours to figure out how to rip out pulseaudio by
its roots, since it clearly isn't working for me. Lovely...)
> Apart from that, it works pretty fine.
> The thing that most surprised me was that after the needed fsck, it had
> converted files with contiguous blocks to big extents ;). Nice.
Um, e2fsck won't convert files to use extents. Once you set the
extents flag, new files that are created will be created with extents,
but existing files are left untouched. Also, some of ext4's
performance improvements will only come after doing a
dump/mke2fs/restore pass. People who are thinking about doing that
would be advised to wait until after 2.6.30 or 2.6.31, though, since
we have a patch that changes how the block/inode allocator works
currently pending in development.
Eventually, I hope the online defragger will be able to fully convert
an ext3 filesystem to use extents, with files defragged and placed in
locations that is as close as possible to a dump/mke2fs/restore pass
--- but we're not there yet. Obviously you'll get a some of the
performance improvements simply going to ext4, and more by enabling
various ext4 features, such as extents et. al. But for example, the
defragger still tries to keep blocks in the same block group, and it's
not aware of the new allocation policies that tries to keep inodes and
blocks within the same flex_bg (which is a collection of block
groups). So that's an example of how the defragger needs to be made
more intelligent, and that work hasn't happened yet.
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