>In that case is there a way to convert the ext3 to ext4 whilst retaining
>all the pre-existing files?  If not then would the system be happy having
>ext4 / partition as well as co-existing ext3 /opt and /home partitions on
>a single system?
To the best of my knowledge ext3 can be converted to ext4 simply by mounting ext3 as ext4 with only minor limitations (same can be done from ext2 to ext3. Therefore formatting ext3 partitions to take advantage of ext4 should not be necessary.

2008/10/4 Mike <mike.cloaked@gmail.com>
Eric Sandeen <sandeen <at> redhat.com> writes:

> Good question.  There's no consensus upstream to drop the "dev" from
> "ext4dev" yet, so it may remain as a boot option for this release, yet.
>
> I think it may technically require a fedora "feature" change to to drop
> the boot argument at this point, but I'm not certain...
>
> It certainly won't be switched in as the *default* for F10, though.

Ultimately when id does become default I wonder what the situation will be
if you install clean for F11+ and make the / partition default formatted
to ext4, but there may be other pre-existing ext3 /opt or /home paritions that
have lots of files on which should not be formatted....

In that case is there a way to convert the ext3 to ext4 whilst retaining
all the pre-existing files?  If not then would the system be happy having
ext4 / partition as well as co-existing ext3 /opt and /home partitions on
a single system?