From: Erik Mouw <erik@harddisk-recovery.com>
To: Kyle Moffett <mrmacman_g4@mac.com>
Cc: Michael Loftis <mloftis@wgops.com>, linux-kernel@vger.kernel.org
Subject: Re: FYI: RAID5 unusably unstable through 2.6.14
Date: Wed, 18 Jan 2006 12:24:31 +0100 [thread overview]
Message-ID: <20060118112431.GA11868@harddisk-recovery.nl> (raw)
In-Reply-To: <D62A7AD5-0954-4FA9-8E20-0E026A3E765A@mac.com>
On Tue, Jan 17, 2006 at 07:12:57PM -0500, Kyle Moffett wrote:
> The most reliable RAID-5 you can build is a 3-drive system. For each
> byte of data, you have a half-byte of parity, meaning that half the
> data-space (not including the parity) can fail without data loss.
> I'm ignoring the issue of rotating parity drive for simplicity, but
> that only affects performance, not the algorithm. If you want any
> kind of _real_ reliability and speed, you should buy a couple good
> hardware RAID-5 units and mirror them in software.
Actually, the most reliable RAID-5 is a 2 drive system, where you have
a full byte of reduncancy for each byte of data. Two drive RAID-5
systems are usually called RAID-1, but if you write out the formulas it
becomes clear that RAID-1 is just a special case of RAID-5.
Erik
--
+-- Erik Mouw -- www.harddisk-recovery.com -- +31 70 370 12 90 --
| Lab address: Delftechpark 26, 2628 XH, Delft, The Netherlands
| Data lost? Stay calm and contact Harddisk-recovery.com
next prev parent reply other threads:[~2006-01-18 11:24 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 [this message]
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
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
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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