From: NeilBrown <neilb@suse.de>
To: Jaromir Capik <jcapik@redhat.com>
Cc: linux-raid@vger.kernel.org
Subject: Re: [RFE] Please, add optional RAID1 feature (= chunk checksums) to make it more robust
Date: Wed, 18 Jul 2012 21:15:37 +1000 [thread overview]
Message-ID: <20120718211537.516b574f@notabene.brown> (raw)
In-Reply-To: <a62c8158-aae7-4924-8408-e0302ff4e9b3@zmail15.collab.prod.int.phx2.redhat.com>
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On Wed, 18 Jul 2012 07:01:48 -0400 (EDT) Jaromir Capik <jcapik@redhat.com>
wrote:
> Hello.
>
> I'd like to ask you to implement the following ...
>
> The current RAID1 solution is not robust enough to protect the data
> against random data corruptions. Such corruptions usually happen
> when an unreadable sector is found by the drive's electronics
> and when the drive's trying to reallocate the sector to the spare area.
> There's no guarantee that the reallocated data will always match
> the original stored data since the drive sometimes can't read the data
> correctly even with several retries. That unfortunately completely masks
> the issue, because the sector can be read by the OS without problems
> even if it doesn't contain correct data.
If a drive ever lets you read incorrect data rather than giving you an error
indication, then the drive is broken by design. Don't use drives that do
that.
> Would it be possible
> to implement chunk checksums to avoid such data corruptions?
No.
NeilBrown
> If a corrupted chunk is encountered, it would be taken from the second
> drive and immediately synced back. This would have a small performance
> and capacity impact (1 sector per chunk to minimize performance impact
> caused by unaligned granularity = 0.78% of the capacity with 64k chunks).
>
> Please, let me know if you find my request reasonable or not.
>
> Thanks in advance.
>
> Regards,
> Jaromir.
>
> --
> Jaromir Capik
> Red Hat Czech, s.r.o.
> Software Engineer / BaseOS
>
> Email: jcapik@redhat.com
> Web: www.cz.redhat.com
> Red Hat Czech s.r.o., Purkynova 99/71, 612 45, Brno, Czech Republic
> IC: 27690016
>
>
> --
> To unsubscribe from this list: send the line "unsubscribe linux-raid" in
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> More majordomo info at http://vger.kernel.org/majordomo-info.html
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next prev parent reply other threads:[~2012-07-18 11:15 UTC|newest]
Thread overview: 36+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <17025a94-1999-4619-b23d-7460946c2f85@zmail15.collab.prod.int.phx2.redhat.com>
2012-07-18 11:01 ` [RFE] Please, add optional RAID1 feature (= chunk checksums) to make it more robust Jaromir Capik
2012-07-18 11:13 ` Mathias Burén
2012-07-18 12:42 ` Jaromir Capik
2012-07-18 11:15 ` NeilBrown [this message]
2012-07-18 13:04 ` Jaromir Capik
2012-07-19 3:48 ` Stan Hoeppner
2012-07-20 12:53 ` Jaromir Capik
2012-07-20 18:24 ` Roberto Spadim
2012-07-20 18:30 ` Roberto Spadim
2012-07-20 20:07 ` Jaromir Capik
2012-07-20 20:21 ` Roberto Spadim
2012-07-20 20:44 ` Jaromir Capik
2012-07-20 20:59 ` Roberto Spadim
2012-07-21 3:58 ` Stan Hoeppner
2012-07-18 11:49 ` keld
2012-07-18 13:08 ` Jaromir Capik
2012-07-18 16:08 ` Roberto Spadim
2012-07-20 10:35 ` Jaromir Capik
2012-07-18 21:02 ` keld
2012-07-18 16:28 ` Asdo
2012-07-20 11:07 ` Jaromir Capik
2012-07-20 11:14 ` Oliver Schinagl
2012-07-20 11:28 ` Jaromir Capik
[not found] <1082734092.338339.1342995087426.JavaMail.root@redhat.com>
2012-07-23 4:29 ` Stan Hoeppner
2012-07-23 9:34 ` Jaromir Capik
2012-07-23 10:53 ` Stan Hoeppner
2012-07-23 17:03 ` Piergiorgio Sartor
2012-07-23 18:24 ` Roberto Spadim
2012-07-23 21:31 ` Drew
2012-07-23 21:42 ` Roberto Spadim
2012-07-24 4:42 ` Stan Hoeppner
2012-07-24 12:51 ` Roberto Spadim
2012-07-27 6:06 ` Adam Goryachev
2012-07-27 13:42 ` Roberto Spadim
2012-07-24 15:09 ` Jaromir Capik
[not found] <1897705147.341625.1342995720661.JavaMail.root@redhat.com>
2012-07-23 4:30 ` Stan Hoeppner
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