From: Scott Carey <scott@richrelevance.com>
To: Alan Hodgson <ahodgson@simkin.ca>
To: pgsql-performance@postgresql.org <pgsql-performance@postgresql.org>
Subject: Re: How to best use 32 15k.7 300GB drives?
Date: Fri, 28 Jan 2011 09:44:33 -0800
Message-ID: <C9683F12.1E3D5%scott@richrelevance.com> (raw)
In-Reply-To: <201101271611.18465@hal.medialogik.com>
On 1/27/11 4:11 PM, "Alan Hodgson" <ahodgson@simkin.ca<mailto:ahodgson@simkin.ca>> wrote:
On January 27, 2011, Robert Schnabel <schnabelr@missouri.edu<mailto:schnabelr@missouri.edu>> wrote:
> So my questions are 1) am I'm crazy for doing this, 2) would you change
> anything and 3) is it acceptable to put the xlog & wal (and perhaps tmp
> filespace) on a different controller than everything else? Please keep
> in mind I'm a geneticist who happens to know a little bit about
> bioinformatics and not the reverse. :-)
>
Putting the WAL on a second controller does help, if you're write-heavy.
I tried separating indexes and data once on one server and didn't really notice that it helped much. Managing the space was problematic. I would suggest putting those together on a single RAID-10 of all the 300GB drives (minus a spare). It will probably outperform separate arrays most of the time, and be much easier to manage.
If you go this route, I suggest two equally sized RAID 10's on different controllers fir index + data, with software raid-0 on top of that. RAID 10 will max out a controller after 6 to 10 drives, usually. Using the OS RAID 0 to aggregate the throughput of two controllers works great.
WAL only has to be a little bit faster than your network in most cases. I've never seen it be a bottleneck on large bulk loads if it is on its own controller with 120MB/sec write throughput. I suppose a bulk load from COPY might stress it a bit more, but CPU ends up the bottleneck in postgres once you have I/O hardware this capable.
--
A hybrid Escalade is missing the point much in the same way that having a diet soda with your extra large pepperoni pizza is missing the point.
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To: pgsql-performance@postgresql.org
Cc: scott@richrelevance.com, ahodgson@simkin.ca
Subject: Re: How to best use 32 15k.7 300GB drives?
In-Reply-To: <C9683F12.1E3D5%scott@richrelevance.com>
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