Re: ext3 and Software RAID

From: Andreas Dilger (adilger@turbolinux.com)
Date: Sun Oct 08 2000 - 00:37:31 EST


Matt Stegman writes:
> A few weeks ago Alan Cox mentioned, in reply to someone asking about
> building an enourmous RAID array,
>
> "Right now 2.2 doesnt support journalling over software raid so that would
> stop you using reiserfs and ext3."
>
> http://kernelnotes.org/lnxlists/linux-kernel/lk_0008_05/msg00009.html
>
> Is this still true? I was going to use 2.2.17, with ext3-0.0.3b, and Ingo
> Molnar's 2.2.17 RAID patch:

This was just discussed on l-k last week. Basically, no it still doesn't
work (not for 2.2 at least). The problem is with RAID doing buffer cache
snooping and causing data to be written out-of-order to disk (on 2.2).
This is fixed in 2.4, but there _may_ still be a problem in 2.4 when
rebuilding the array (on disk failure) in 2.4... I'm not too sure of
the latter though...

Cheers, Andreas

-- 
Andreas Dilger  \ "If a man ate a pound of pasta and a pound of antipasto,
                 \  would they cancel out, leaving him still hungry?"
http://www-mddsp.enel.ucalgary.ca/People/adilger/               -- Dogbert
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