From: Neil Brown <neilb@suse.de>
To: Leif Nixon <nixon@nsc.liu.se>
Cc: linux-raid@vger.kernel.org
Subject: Re: raid6 check/repair
Date: Fri, 16 Nov 2007 15:26:18 +1100 [thread overview]
Message-ID: <18237.7146.783687.826984@notabene.brown> (raw)
In-Reply-To: message from Leif Nixon on Thursday November 15
On Thursday November 15, nixon@nsc.liu.se wrote:
> Hi,
>
> I have been looking a bit at the check/repair functionality in the
> raid6 personality.
>
> It seems that if an inconsistent stripe is found during repair, md
> does not try to determine which block is corrupt (using e.g. the
> method in section 4 of HPA's raid6 paper), but just recomputes the
> parity blocks - i.e. the same way as inconsistent raid5 stripes are
> handled.
>
> Correct?
Correct!
The mostly likely cause of parity being incorrect is if a write to
data + P + Q was interrupted when one or two of those had been
written, but the other had not.
No matter which was or was not written, correctly P and Q will produce
a 'correct' result, and it is simple. I really don't see any
justification for being more clever.
NeilBrown
next prev parent reply other threads:[~2007-11-16 4:26 UTC|newest]
Thread overview: 20+ messages / expand[flat|nested] mbox.gz Atom feed top
2007-11-15 15:28 raid6 check/repair Leif Nixon
2007-11-16 4:26 ` Neil Brown [this message]
-- strict thread matches above, loose matches on Subject: below --
2007-11-21 13:25 Thiemo Nagel
2007-11-22 3:55 ` Neil Brown
2007-11-22 16:51 ` Thiemo Nagel
2007-11-27 5:08 ` Bill Davidsen
2007-11-29 6:04 ` Neil Brown
2007-11-29 6:01 ` Neil Brown
2007-11-29 19:30 ` Bill Davidsen
2007-11-29 23:17 ` Eyal Lebedinsky
2007-11-30 14:42 ` Thiemo Nagel
[not found] ` <1196650421.14411.10.camel@elara.tcw.local>
[not found] ` <47546019.5030300@ph.tum.de>
2007-12-04 21:07 ` Peter Grandi
2007-12-05 6:53 ` Mikael Abrahamsson
2007-12-05 9:00 ` Leif Nixon
2007-12-05 20:31 ` Bill Davidsen
2007-12-06 18:27 ` Andre Noll
2007-12-07 17:34 ` Gabor Gombas
2007-11-30 18:34 ` Thiemo Nagel
2007-11-21 13:45 Thiemo Nagel
2007-12-14 15:25 ` Thiemo Nagel
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