Date: Mon, 30 Jun 2003 14:08:04 +0200
From: Stephan von Krawczynski <skraw@ithnet.com>
To: Marcelo Tosatti <marcelo@conectiva.com.br>
Cc: linux-kernel@vger.kernel.org, stoffel@lucent.com, willy@w.ods.org,
       kpfleming@cox.net, gibbs@scsiguy.com, green@namesys.com
Subject: Re: Undo aic7xxx changes (now rc7+aic20030603)
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On Mon, 30 Jun 2003 08:39:38 -0300 (BRT)
Marcelo Tosatti <marcelo@conectiva.com.br> wrote:

> 
> 
> On Mon, 30 Jun 2003, Stephan von Krawczynski wrote:
> 
> > Hello all,
> >
> > it looks like the problem gets worse currently. This is the second day I
> > see 4 verification errors. This is with kernel 2.4.22-pre2 now.
> 
> 
> As far as I understood, the tape is corrupting the data (or writting, or
> when reading back).
> 
> Is this correct?

Actually my guess is that the _data_ itself is not corrupt, neither the
original set located on 3ware RAID nor the backup'ed set on aic-connected SDLT.
The problem is - according to my personal opinion - flawed during the readback
that occurs while verifying. I do not know if the data is already corrupted by
the aic-driver (less probable currently) or some flaw inside the caching of the
_original_ set. The situation is complex because of the multiple involved
subsystems. 

My experience is this:

If you reboot and make backup/verify cycle from 3ware to aic/tape everything
seems fine.

If you reboot and push data over NFS to 3ware-disk, then do the backup/verify
cycle (with this data) from 3ware to aic/tape the corruption is very likely.

If you do try another verify run of the data you see corruptions happen on
_other_ files than the verify before. It is therefore unlikely that both data
"ends" are part of the problem, because you would expect the same corruptions
to show up - at least this is my hope.

Regards,
Stephan

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