From: Mark Kirkwood <mark.kirkwood@catalyst.net.nz>
To: Jan Nielsen <jan.sture.nielsen@gmail.com>
Cc: pgsql-performance@postgresql.org
Subject: Re: Configuration Recommendations
Date: Thu, 24 May 2012 16:59:44 +1200
Message-ID: <4FBDC040.2000406@catalyst.net.nz> (raw)
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<CANxH4hH07eZRPe6Bvq3Op+taeWd2hz_Z9EqOFA5K35m31-MKPw@mail.gmail.com>
On 20/05/12 03:47, Jan Nielsen wrote:
> In this test, the local mount's buffered reads perform best around RA~10k @
> 150MB/sec then starts a steady decline. The SAN mount has a similar but
> more subtle decline with a maximum around RA~5k @ 80MB/sec but with much
> greater variance. I was surprised at the 80MB/sec for the SAN - I was
> expecting 150MB/sec - and I'm also surprised at the variance. I understand
> that there are many more elements involved for the SAN: more drives,
> network overhead& latency, iscsi, etc. but I'm still surprised.
>
> Is this expected behavior for a SAN mount or is this a hint at some
> misconfiguration? Thoughts?
>
>
Is the SAN mount via iSCSI? If so and also if the connection is a
single 1Gbit interface then 80MB/s is reasonable. You might get closer
to 100MB/s by tweaking things like MTU for the interface concerned, but
to get more performance either bonding several 1Gbit links or using
10Gbit is required.
Regards
Mark
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To: pgsql-performance@postgresql.org
Cc: mark.kirkwood@catalyst.net.nz, jan.sture.nielsen@gmail.com
Subject: Re: Configuration Recommendations
In-Reply-To: <4FBDC040.2000406@catalyst.net.nz>
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