Subject: Re: Slow restoration question
From: Mark Lewis <mark.lewis@mir3.com>
To: Brendan Duddridge <brendan@clickspace.com>
Cc: "Jim C.Nasby" <jnasby@pervasive.com>, Eric Lam <elam@lisasoft.com>,
	pgsql-performance@postgresql.org
In-Reply-To: <622925BE-A31E-42FD-AF6A-68DDF3B4A1B7@clickspace.com>
References: <444F24E9.2010907@lisasoft.com>
	<20060502171617.GZ97354@pervasive.com>
	<622925BE-A31E-42FD-AF6A-68DDF3B4A1B7@clickspace.com>
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Organization: MIR3, Inc.
Date: Tue, 02 May 2006 11:49:15 -0700
Message-Id: <1146595755.12053.111.camel@archimedes>
Mime-Version: 1.0

They are not equivalent.  As I understand it, RAID 0+1 performs about
the same as RAID 10 when everything is working, but degrades much less
nicely in the presence of a single failed drive, and is more likely to
suffer catastrophic data loss if multiple drives fail.

-- Mark

On Tue, 2006-05-02 at 12:40 -0600, Brendan Duddridge wrote:
> Everyone here always says that RAID 5 isn't good for Postgres. We  
> have an Apple Xserve RAID configured with RAID 5. We chose RAID 5  
> because Apple said their Xserve RAID was "optimized" for RAID 5. Not  
> sure if we made the right decision though. They give an option for  
> formatting as RAID 0+1. Is that the same as RAID 10 that everyone  
> talks about? Or is it the reverse?
> 
> Thanks,
> 
> ____________________________________________________________________
> Brendan Duddridge | CTO | 403-277-5591 x24 |  brendan@clickspace.com
> 
> ClickSpace Interactive Inc.
> Suite L100, 239 - 10th Ave. SE
> Calgary, AB  T2G 0V9
> 
> http://www.clickspace.com
> 
> On May 2, 2006, at 11:16 AM, Jim C. Nasby wrote:
> 
> > On Wed, Apr 26, 2006 at 05:14:41PM +0930, Eric Lam wrote:
> >> all dumpfiles total about 17Gb. It has been running for 50ish hrs  
> >> and up
> >> to about the fourth file (5-6 ish Gb) and this is on a raid 5 server.
> >
> > RAID5 generally doesn't bode too well for performance; that could be
> > part of the issue.
> > -- 
> > Jim C. Nasby, Sr. Engineering Consultant      jnasby@pervasive.com
> > Pervasive Software      http://pervasive.com    work: 512-231-6117
> > vcard: http://jim.nasby.net/pervasive.vcf       cell: 512-569-9461
> >
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> >                http://archives.postgresql.org
> >
> 
> 
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