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From: Tomas Vondra <tv@fuzzy.cz>
To: pgsql-performance@postgresql.org
Subject: Re: H800 + md1200 Performance problem
Date: Tue, 03 Apr 2012 15:21:42 +0200
Message-ID: <4F7AF966.20809@fuzzy.cz> (raw)
In-Reply-To: <CAMAsR=7g5PXU45+Z3aBW+ur-kPQKiW2MG=NJ3TOqNn6iqaVCVw@mail.gmail.com>
References: <CAMAsR=4acKwYjow-VWQ0xH0+WjXEtVJWxP0A0y4vx=oyr5fhpQ@mail.gmail.com>
	<920BB532-C321-45A3-851E-8B688A5963F7@yahoo.com>
	<CAMAsR=7g5PXU45+Z3aBW+ur-kPQKiW2MG=NJ3TOqNn6iqaVCVw@mail.gmail.com>

On 3.4.2012 14:59, Cesar Martin wrote:
> Hi Mike,
> Thank you for your fast response.
> 
> blockdev --getra /dev/sdc
> 256

That's way too low. Is this setting the same on both machines?

Anyway, set it to 4096, 8192 or even 16384 and check the difference.

BTW explain analyze is nice, but it's only half the info, especially
when the issue is outside PostgreSQL (hw, OS, ...). Please, provide
samples from iostat / vmstat or tools like that.

Tomas

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