Message-ID: <467B0568.9040001@g2switchworks.com>
Date: Thu, 21 Jun 2007 18:10:32 -0500
From: Scott Marlowe <smarlowe@g2switchworks.com>
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To: Andrew Sullivan <ajs@crankycanuck.ca>
CC: pgsql-performance@postgresql.org
Subject: Re: Performance query about large tables, lots of concurrent
 access
References: <4676DD57.7070304@metacarta.com>
	<20070620175300.GN30369@alvh.no-ip.org>
	<46796A08.8080601@metacarta.com>
	<200706201425.28557.sthomas@leapfrogonline.com>
	<46799C45.7080805@metacarta.com>
	<4679AE24.9070005@g2switchworks.com>
	<4679B6C7.3080207@metacarta.com> <467A9CE5.508@g2switchworks.com>
	<467AA77D.3030204@metacarta.com>
	<20070621171148.GC5500@phlogiston.dyndns.org>
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Andrew Sullivan wrote:
> On Thu, Jun 21, 2007 at 12:29:49PM -0400, Karl Wright wrote:
>   
>> I checked the disk picture - this is a RAID disk array with 6 drives, 
>> with a bit more than 1Tbyte total storage.  15,000 RPM.  It would be 
>> hard to get more/faster disk than that.
>>     
>
> What kind of RAID?  It's _easy_ to get faster disk that 6 drives in
> RAID5, even if they're 15,000 RPM.  The rotation speed is the least
> of your problems in many RAID implementations.
>   
Also, the controller means a lot.  I'd rather have a 4 disk RAID-10 with 
an Areca card with BBU Cache than a 16 disk RAID 5 on an adaptec (with 
or without cache... :) )