From: Roy Sigurd Karlsbakk <roy@karlsbakk.net>
To: stan@hardwarefreak.com
Cc: linux-raid@vger.kernel.org, Mikael Abrahamsson <swmike@swm.pp.se>
Subject: Re: Suboptimal raid6 linear read speed
Date: Sat, 19 Jan 2013 14:21:59 +0100 (CET) [thread overview]
Message-ID: <20597456.6.1358601718986.JavaMail.root@zimbra> (raw)
In-Reply-To: <50F9D32F.7090606@hardwarefreak.com>
> >> The probability of a URE during rebuild increases with the number
> >> and
> >> size of the source drives being read to rebuild the failed drive.
> >> Thus
> >> the probability of encountering a URE in the 1:1 drive scenario is
> >> extremely low, close to zero if you believe manufacturer specs.
> >
> > For a 2TB drive and BER 10^-14 (common for non-enterprise drives),
> > the
> > probability is 1/6 of a single URE for a read of the entire drive.
>
> If my math is correct, with a URE rate of 10E14, that's one URE for
> every ~12.5TB read. So theoretically one would have to read the entire
> 2TB drive more than 6 times before hitting the first URE. So it seems
> unlikely that one would hit a URE during a mirror rebuild with such a
> 2TB drive.
ok, perhaps, maybe, but then it's 17% chance of losing data after a mirror or raid-5 rebuild with 2TB drives, or the double of that if using 4TB drives. That's not very amusing…
Vennlige hilsener / Best regards
roy
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prev parent reply other threads:[~2013-01-19 13:21 UTC|newest]
Thread overview: 46+ messages / expand[flat|nested] mbox.gz Atom feed top
2013-01-15 12:33 Suboptimal raid6 linear read speed Peter Rabbitson
2013-01-15 12:45 ` Mikael Abrahamsson
2013-01-15 12:56 ` Peter Rabbitson
2013-01-15 16:13 ` Mikael Abrahamsson
2013-01-15 12:49 ` Phil Turmel
2013-01-15 12:55 ` Peter Rabbitson
2013-01-15 17:09 ` Charles Polisher
2013-01-15 19:57 ` keld
2013-01-16 4:43 ` Charles Polisher
2013-01-16 6:37 ` Tommy Apel Hansen
2013-01-16 9:36 ` keld
2013-01-16 16:09 ` Charles Polisher
2013-01-16 20:40 ` EJ Vincent
2013-01-15 23:17 ` Phil Turmel
2013-01-16 2:48 ` Stan Hoeppner
2013-01-16 2:58 ` Peter Rabbitson
2013-01-16 20:29 ` Stan Hoeppner
2013-01-16 21:20 ` Roy Sigurd Karlsbakk
2013-01-17 15:51 ` Mikael Abrahamsson
2013-01-18 8:31 ` Stan Hoeppner
2013-01-18 9:18 ` Mikael Abrahamsson
2013-01-18 22:56 ` Stan Hoeppner
2013-01-19 7:43 ` Mikael Abrahamsson
2013-01-19 22:48 ` Stan Hoeppner
2013-01-19 23:51 ` Maarten
2013-01-20 0:16 ` Chris Murphy
2013-01-20 0:49 ` Maarten
2013-01-20 1:37 ` Phil Turmel
2013-01-20 9:44 ` Chris Murphy
2013-01-20 6:26 ` Mikael Abrahamsson
2013-01-20 9:39 ` Chris Murphy
2013-01-20 16:55 ` Mikael Abrahamsson
2013-01-20 17:15 ` Chris Murphy
2013-01-20 17:17 ` Mikael Abrahamsson
2013-01-20 17:20 ` Chris Murphy
2013-01-19 23:53 ` Phil Turmel
2013-01-20 9:04 ` Wolfgang Denk
2013-01-20 19:28 ` Peter Grandi
2013-01-20 21:09 ` Mikael Abrahamsson
2013-01-20 21:50 ` Peter Grandi
2013-01-21 5:24 ` Mikael Abrahamsson
2013-01-21 14:40 ` Peter Rabbitson
2013-01-21 20:32 ` Peter Grandi
2013-01-21 20:55 ` Peter Grandi
2013-01-21 22:00 ` Peter Grandi
2013-01-19 13:21 ` Roy Sigurd Karlsbakk [this message]
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