Re: random_page_costs - are defaults of 4.0 realistic for SCSI RAID 1

From: Gregory Stark <stark(at)enterprisedb(dot)com>
To: "Decibel!" <decibel(at)decibel(dot)org>
Cc: "Jean-David Beyer" <jeandavid8(at)verizon(dot)net>, <pgsql-performance(at)postgresql(dot)org>
Subject: Re: random_page_costs - are defaults of 4.0 realistic for SCSI RAID 1
Date: 2007-09-11 23:02:46
Message-ID: 87r6l4ajqh.fsf@oxford.xeocode.com
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"Decibel!" <decibel(at)decibel(dot)org> writes:

> On Tue, Sep 11, 2007 at 02:49:28PM -0400, Jean-David Beyer wrote:
>> It is tricky for me to find a big enough file to test. I tried one of the
>
> dd if=/dev/zero of=bigfile bs=8192 count=1000000

On linux another useful trick is:

echo 1 > /proc/sys/vm/drop_caches

Also, it helps to run a "vmstat 1" in another window and watch the bi and bo
columns.

--
Gregory Stark
EnterpriseDB http://www.enterprisedb.com

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