On Sat, 16 Jan 2010 18:52:53 -0800
John Jason Jordan <[email protected]> dijo:
>I have several rescue CDs, from Knoppix to smaller command line only
>disks. Guess what? They're all too old to be able to fix an ext4
>filesystem. My very, very dim understanding is that older systems
>(with ext3) can read/write to an ext4 filesystem, but the older e2fsck
>won't work. I may well be wrong about the read/write - that is, I may
>have it backwards.
I finally found the forwards compatibility answer:
.. Compatibility
The ext4 filesystem is backward compatible with ext3 and ext2,
making it possible to mount ext3 and ext2 filesystems as ext4. This
will already slightly improve performance, because certain new features
of ext4 can also be used with ext3 and ext2, such as the new block
allocation algorithm.
The ext3 file system is partially forward compatible with ext4,
that is, an ext4 filesystem can be mounted as an ext3 partition
(using "ext3" as the filesystem type when mounting). However, if
the ext4 partition uses extents (a major new feature of ext4), then
the ability to mount the file system as ext3 is lost.
<Wikipedia>
If you have any files over 512 MB on an ext4 filesystem you will
definitely have extents. Just one distro ISO would render your
filesystem unmountable by an older live CD.
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