From: Luke Lonergan <llonergan@greenplum.com>
To: Mark Kirkwood <markir@paradise.net.nz>
Cc: Dan Gorman <dgorman@hi5.com>
Cc: Joshua D. Drake <jd@commandprompt.com>
Cc: Craig A. James <cjames@modgraph-usa.com>
Cc: pgsql-performance@postgresql.org
Subject: Re: Reliability recommendations
Date: Fri, 24 Feb 2006 22:22:49 -0800
Message-ID: <C02537B9.1DC8D%llonergan@greenplum.com> (raw)
In-Reply-To: <43FFF4EF.6060601@paradise.net.nz>
Mark,
On 2/24/06 10:10 PM, "Mark Kirkwood" <markir@paradise.net.nz> wrote:
> Well, since this is always fun (2G memory, 3Ware 7506, 4xPATA), writing:
>
> $ dd if=/dev/zero of=/data0/dump/bigfile bs=8k count=500000
> 500000 records in
> 500000 records out
> 4096000000 bytes transferred in 32.619208 secs (125570185 bytes/sec)
> Reading:
>
> $ dd of=/dev/null if=/data0/dump/bigfile bs=8k count=500000
> 500000 records in
> 500000 records out
> 4096000000 bytes transferred in 24.067298 secs (170189442 bytes/sec)
Not bad at all! I have one of these cards in my home machine running WinXP
and it's not nearly this fast.
> Hmmm - a bit humbled by Luke's machinery :-), however, mine is probably
> competitive on (MB/s)/$....
Not sure - the machines I cite are about $10K each. The machine you tested
was probably about $1500 a few years ago (my guess), and with a 5:1 ratio in
speed versus about a 6:1 ratio in price, we're not too far off in MB/s/$
after all :-)
> It would be interesting to see what Dan's system would do on a purely
> sequential workload - as 40-50MB of purely random IO is high.
Yeah - that is really high if the I/O is really random. I'd normally expect
maybe 500-600 iops / second and if each IO is 8KB, that would be 4MB/s. The
I/O is probably not really completely random, or it's random over cachable
bits of the occupied disk area.
- Luke
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To: pgsql-performance@postgresql.org
Cc: llonergan@greenplum.com, markir@paradise.net.nz, dgorman@hi5.com, jd@commandprompt.com, cjames@modgraph-usa.com
Subject: Re: Reliability recommendations
In-Reply-To: <C02537B9.1DC8D%llonergan@greenplum.com>
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