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From: "Mark Powell" <M.S.Powell@salford.ac.uk>
To: Alexey Shuvaev <shuvaev@physik.uni-wuerzburg.de>
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Cc: FreeBSD Current <freebsd-current@freebsd.org>, ticso@cicely.de,
	Mark Powell <M.S.Powell@salford.ac.uk>
Subject: Re: Apparently spurious ZFS CRC errors (was Re: ZFS data error
 without reasons)
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On Wed, 25 Mar 2009, Alexey Shuvaev wrote:

> I don't use zfs, just ufs2 + soft updates, but I see sometimes rather
> heavy data corruption (most often on / filesystem).
> No kernel messages, I can shut down the system successfully just
> to find the remnants of filesystems on the next boot.
> It doesn't happen often, I think compiling ports in a jail + some
> activity in the host increase the probability of a failure.
>
> The drive is:
> ATA channel 3:
>    Master:  ad6 <WDC WD5000AAKS-00C8A0/12.01C02> SATA revision 2.x
>
> hw.ata.wc=1 (default)

Have you tried turning WC off to see if it improves matters?
   Cheers.

-- 
Mark Powell - UNIX System Administrator - The University of Salford
Information & Learning Services, Clifford Whitworth Building,
Salford University, Manchester, M5 4WT, UK.
Tel: +44 161 295 6843  Fax: +44 161 295 5888  www.pgp.com for PGP key