From: Pavel Machek <pavel@ucw.cz>
To: Bill Davidsen <davidsen@tmr.com>
Cc: Phillip Susi <psusi@cfl.rr.com>, linux-kernel@vger.kernel.org
Subject: Re: FYI: RAID5 unusably unstable through 2.6.14
Date: Wed, 8 Feb 2006 21:58:03 +0000 [thread overview]
Message-ID: <20060208215802.GE2353@ucw.cz> (raw)
In-Reply-To: <43E2834F.8040009@tmr.com>
Hi!
> >If 1 disk has a 1/1000 chance of failure, then
> >2 disks have a (1/1000)^2 chance of double failure, and
> >3 disks have a (1/1000)^2 * 3 chance of double failure
> >4 disks have a (1/1000)^2 * 7 chance of double failure
>
> After the first drive fails you have no redundancy, the
> chance of an additional failure is linear to the number
> of remaining drives.
>
> Assume:
> p - probability of a drive failing in unit time
> n - number of drives
> F - probability of double failure
>
> The chance of a single drive failure is n*p. After that
<pedantic>
Actually it is not. Imagine 100 drives with 10% failure rate each. You
can't have probability of 1000%...
</>
Pavel
--
Thanks, Sharp!
next prev parent reply other threads:[~2006-02-09 17:06 UTC|newest]
Thread overview: 44+ messages / expand[flat|nested] mbox.gz Atom feed top
2006-01-17 19:35 FYI: RAID5 unusably unstable through 2.6.14 Cynbe ru Taren
2006-01-17 19:39 ` Benjamin LaHaise
2006-01-17 20:13 ` Martin Drab
2006-01-17 23:39 ` Michael Loftis
2006-01-18 2:30 ` Martin Drab
2006-02-02 20:33 ` Bill Davidsen
2006-02-03 0:57 ` Martin Drab
2006-02-03 1:13 ` Martin Drab
2006-02-03 15:41 ` Phillip Susi
2006-02-03 16:13 ` Martin Drab
2006-02-03 16:38 ` Phillip Susi
2006-02-03 17:22 ` Roger Heflin
2006-02-03 19:38 ` Phillip Susi
2006-02-03 17:51 ` Martin Drab
2006-02-03 19:10 ` Roger Heflin
2006-02-03 19:12 ` Martin Drab
2006-02-03 19:41 ` Phillip Susi
2006-02-03 19:45 ` Martin Drab
2006-01-17 19:56 ` Kyle Moffett
2006-01-17 19:58 ` David R
2006-01-17 20:00 ` Kyle Moffett
2006-01-17 23:27 ` Michael Loftis
2006-01-18 0:12 ` Kyle Moffett
2006-01-18 11:24 ` Erik Mouw
2006-01-18 0:21 ` Phillip Susi
2006-01-18 0:29 ` Michael Loftis
2006-01-18 2:10 ` Phillip Susi
2006-01-18 3:01 ` Michael Loftis
2006-01-18 16:49 ` Krzysztof Halasa
2006-01-18 16:47 ` Krzysztof Halasa
2006-02-02 22:10 ` Bill Davidsen
2006-02-08 21:58 ` Pavel Machek [this message]
2006-01-18 10:54 ` Helge Hafting
2006-01-18 16:15 ` Mark Lord
2006-01-18 17:32 ` Alan Cox
2006-01-19 15:59 ` Mark Lord
2006-01-19 16:25 ` Alan Cox
2006-02-08 14:46 ` Alan Cox
2006-01-18 23:37 ` Neil Brown
2006-01-19 15:53 ` Mark Lord
2006-01-19 0:13 ` Neil Brown
-- strict thread matches above, loose matches on Subject: below --
2006-02-03 17:00 Salyzyn, Mark
2006-02-03 17:39 ` Martin Drab
2006-02-03 19:46 ` Phillip Susi
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