From: Andreas Dilger <adilger@sun.com>
Subject: Re: ll_ver_fs data verification failure - 96TB fs
Date: Thu, 06 Aug 2009 14:50:02 -0600
Message-ID: <20090806205002.GH3340@webber.adilger.int>
References: <28623.1249307676@gamaville.dokosmarshall.org>
 <20090806200400.GC1800@shell> <18249.1249591034@alphaville.usa.hp.com>
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Cc: Valerie Aurora <vaurora@redhat.com>, linux-ext4@vger.kernel.org
To: Nick Dokos <nicholas.dokos@hp.com>
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On Aug 06, 2009  16:37 -0400, Nick Dokos wrote:
> I did that to begin with but the problem turns out to be much more
> mundane: there was an IO error on one of the volumes. It wasn't quite
> obvious (no red lights going off) but there *was* a message in
> /var/log/messages - unfortunately I missed it. I eventually recreated
> the error by trying to read the file with ``od -c'' and then went back
> and found the original error. I don't know why/how ll_ver_fs managed to
> read the offset and come up with a 1M difference[1] -- ``od -c'' failed with
> a big thud.

Can you have a look at the error handling in ll_ver_fs at that point?
It seems that it might just have re-used the previous 1MB buffer, but
didn't detect/report the error from the read, which would itself be bad.

Cheers, Andreas
--
Andreas Dilger
Sr. Staff Engineer, Lustre Group
Sun Microsystems of Canada, Inc.