User-Agent: Microsoft-Entourage/11.2.5.060620
Date: Mon, 11 Sep 2006 16:37:36 -0700
Subject: Re: Configuring System for Speed
From: "Luke Lonergan" <llonergan@greenplum.com>
To: "Brian Wipf" <brian@clickspace.com>
cc: pgsql-performance@postgresql.org
Message-ID: <C12B4150.30A12%llonergan@greenplum.com>
Thread-Topic: [PERFORM] Configuring System for Speed
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Brian,

On 9/11/06 8:50 AM, "Brian Wipf" <brian@clickspace.com> wrote:

> That's a great idea. One question though. If I put all 16 drives in a
> RAID 10 for the database, where should I put the logs? On that large
> RAID set? If I use a RAID controller with a BB cache for the mirrored
> laptop drives, might I be able to use that for the logs and OS?

I think I'd probably reserve a couple of the data drives for the WAL, at 16
you have far oversubscribed non-MPP postgres' ability to use them for
bandwidth and you'd only lose about 5% of your seek performance by dropping
a couple of drives.

The laptop drives are really slow, so putting your WAL on them might be a
net loss.

Alternately you could go with dual SFF SAS drives, which are the same
physical size as the laptop drives but are 10,000 RPM SCSI equivalent.  Heat
removal will be more of an issue with these potentially, especially if you
have a lot of activity on them.

- Luke