linux-kernel.vger.kernel.org archive mirror
 help / color / mirror / Atom feed
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

  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

Reply instructions:

You may reply publicly to this message via plain-text email
using any one of the following methods:

* Save the following mbox file, import it into your mail client,
  and reply-to-all from there: mbox

  Avoid top-posting and favor interleaved quoting:
  https://en.wikipedia.org/wiki/Posting_style#Interleaved_style

* Reply using the --to, --cc, and --in-reply-to
  switches of git-send-email(1):

  git send-email \
    --in-reply-to=20060118112431.GA11868@harddisk-recovery.nl \
    --to=erik@harddisk-recovery.com \
    --cc=linux-kernel@vger.kernel.org \
    --cc=mloftis@wgops.com \
    --cc=mrmacman_g4@mac.com \
    /path/to/YOUR_REPLY

  https://kernel.org/pub/software/scm/git/docs/git-send-email.html

* If your mail client supports setting the In-Reply-To header
  via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).