Date: Tue, 22 Aug 2006 06:02:38 -0400
From: Michael Stone <mstone+postgres@mathom.us>
Subject: Re: Storage Options
In-reply-to: <1156197051.15743.50.camel@dogma.v10.wvs>
To: pgsql-performance@postgresql.org
Mail-followup-to: pgsql-performance@postgresql.org
Message-id: <20060822100236.GW2900@mathom.us>
MIME-version: 1.0
Content-type: text/plain; charset=us-ascii; format=flowed
Content-disposition: inline
References: <1156197051.15743.50.camel@dogma.v10.wvs>
User-Agent: Mutt/1.5.12-2006-07-14

On Mon, Aug 21, 2006 at 02:50:51PM -0700, Jeff Davis wrote:
>the NetApp over NFS, so I am not sure what performance to expect. Any
>suggestions about using network storage like this for the database?

Don't. Unless you're using a very small (toy-scale) database, the netapp 
storage is way too expensive for the kind of usage you see with a 
database application. You're much better off buying much cheaper storage 
twice and using a database replication solution than either choking a 
really expensive netapp or getting lousy performance from the same. The 
netapps have their niche, but database storage isn't it. (Peformance in 
general really isn't it--the advantages are managability, snapshotting, 
and cross-platform data exchange. It may be that those factors are 
important enough to make that a good solution for your particular 
situation, but they're generally not particularly relevant in the 
postgres space.)

>Is there any consensus on whether to do WAL on a RAID-1 and PGDATA on a
>RAID-10 versus everything on a RAID-10? How does the number of disks I
>have affect this decision (I will probably have 4-8 disks per server).

You can't get a good answer without testing with your actual data. I'd 
suspect that with such a low number of disks you're better off with a 
single array, assuming that you have a good bbu raid controller and 
assuming that you're not doing write-mostly transaction work. But 
testing with your actual workload is the only way to really know.

Mike Stone