Re: document ext3 requirements

Duane Griffin
2009-01-04T14:24:56Z

2009/1/4 <Valdis.Kletnieks@vt.edu>:
> On Sun, 04 Jan 2009 00:41:51 GMT, Duane Griffin said:
>
>> I agree, it isn't a great situation. Nonetheless, it has always been
>> thus for ext3, and so far we've muddled along. Unless and until we can
>> replay the journal in-memory without touching the on-disk data, we are
>> stuck with it.
>
> Is there a way using md/dm/lvm etc to make the source partition R/O and
> replay the journal onto a CoW snapshop? Admittedly, not easy to do inside
> the 'mount' command itself, but at least it might be workable for LiveCD R/O
> mounts and forensics work, where you can *tell* beforehand that's what you
> want and can jump through setup games before doing the mount...

Yes, something like that is best practice, as I understand it. The
LiveCD init scripts could check whether they are about to R/O mount an
ext[34] filesystem needing recovery and either refuse with a useful
message to the user, or even automatically create and mount a COW
snapshot, as you described. They'd still need to warn the user though,
since things like remounting R/W wouldn't work as expected.

Cheers,
Duane.

--
"I never could learn to drink that blood and call it wine" - Bob Dylan