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Re: Article about PostgreSQL and RAID in Brazil

From: "Jim C(dot) Nasby" <decibel(at)decibel(dot)org>
To: Josh Berkus <josh(at)agliodbs(dot)com>
Cc: ricardo(at)sqlmagazine(dot)com(dot)br, pgsql-performance(at)postgresql(dot)org,br(at)postgresql(dot)org
Subject: Re: Article about PostgreSQL and RAID in Brazil
Date: 2004-09-16 20:48:53
Message-ID: 20040916204853.GF56059@decibel.org (view raw or flat)
Thread:
Lists: pgsql-performance
On Thu, Sep 16, 2004 at 10:50:33AM -0700, Josh Berkus wrote:
> The second step is to have lots of disks; 5 drives is a minimum for really 
> good performance.   3-drive RAID5, in particular, is a poor performer for 
> PostgreSQL, often resulting in I/O that is 40% or less as efficient as a 
> single disk due to extremely slow random seeks and little parallelization.
> 
> Once you have 6 drives or more, opinions are divided on whether RAID 10 or 
> RAID 5 is better.   I think it partly depends on your access pattern.

What about benefits from putting WAL and pg_temp on seperate drives?
Specifically, we have a box with 8 drives, 2 in a mirror with the OS and
WAL and pg_temp; the rest in a raid10 with the database on it. Do you
think it would have been better to make one big raid10? What if it was
raid5? And what if it was only 6 drives total?
-- 
Jim C. Nasby, Database Consultant               decibel(at)decibel(dot)org 
Give your computer some brain candy! www.distributed.net Team #1828

Windows: "Where do you want to go today?"
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FreeBSD: "Are you guys coming, or what?"

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