Re: ext3 to ext2 convertion

[Levi Waldron <levi.waldron@utoronto.ca>]

On February 13, 2003 01:19 pm, Bruno Diniz de Paula wrote:
> Hi,
>
> how can I convert a ext3 partition to ext2? Is it only to change the
> type in fstab and reboot? How can I synchronize the modification stored
> in the journal file?

>From http://www.kernel.org/pub/linux/kernel/people/sct/ext3/README :


How to move back from ext3 to ext2
----------------------------------

It's quite easy.  If you unmount an ext3 filesystem cleanly, then you
can remount it as ext2 without any other commands.  If you crash and are
left with an unclean ext3 filesystem, on the other hand, the filesystem
will prevent you from mounting it as ext2: it is not safe to mount it
until you have recovered the journal, and the only way to do that for
now is to mount it as ext3.

However, if for any reason you do have an ext3 filesystem which you want
to convert permanently back to ext2, whether it was cleanly unmounted or
not, you can use "debugfs" from e2fsprogs-1.17 or later to do it.
First, run debugfs and open the filesystem (the -w flag means open for
write, and the -f flag forces it to open the filesystem even if there
are unknown journal flags set):

    [root@sarek /root]# debugfs
    debugfs 1.18, 11-Nov-1999 for EXT2 FS 0.5b, 95/08/09
    debugfs:  open -f -w /dev/sdb1 

Now, use "features" to see which feature bits are set on the filesystem:

    debugfs:  features
    Filesystem features: has_journal filetype sparse_super

We want to clear the journal bits, then we can quit:

    debugfs:  features -has_journal -needs_recovery
    Filesystem features: filetype sparse_super
    debugfs:  quit
    [root@sarek /root]# debugfs

That's it!