From: Greg Smith <gsmith@gregsmith.com>
To: pgsql-performance@postgresql.org
Subject: Re: WALL on controller without battery?
Date: Wed, 11 Jul 2007 19:01:10 -0400 (EDT)
Message-ID: <Pine.GSO.4.64.0707111844270.15084@westnet.com> (raw)
In-Reply-To: <cone.1184186086.804659.9511.5001@35st.simplicato.com>
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<46953359.5060404@commandprompt.com>
<cone.1184186086.804659.9511.5001@35st.simplicato.com>
On Wed, 11 Jul 2007, Francisco Reyes wrote:
> I am re-working the specs of the machine to try and get a 4port 3ware to have
> the battery backup.
That's really not necessary, it just would be better (and obviously more
expensive). The warnings you've been getting here have been to let you
know that you absolutely can't put the WAL on the controller with the OS
disks attached without making compromises you probably won't be happy
with.
> During peak operation there will be about 5 to 20 updates per second
> with a handfull of reads.
There really is no reason you need to be concerned about WAL from a
performance perspective if this is your expected workload. If you're
working with a tight budget, the original design you had was perfectly
fine. Just use all the disks on the big controller as a large volume, put
both the database and the WAL on there, and don't even bother trying to
separate out the WAL. If you expected hundreds of updates per second,
that's where you need to start thinking about a separate WAL disk, and
even then with 8 disks to spread the load out and a good caching
controller you might still be fine.
--
* Greg Smith gsmith@gregsmith.com http://www.gregsmith.com Baltimore, MD
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To: pgsql-performance@postgresql.org
Cc: gsmith@gregsmith.com
Subject: Re: WALL on controller without battery?
In-Reply-To: <Pine.GSO.4.64.0707111844270.15084@westnet.com>
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