Re: Scaling further up

From: Paul Thomas <paul(at)tmsl(dot)demon(dot)co(dot)uk>
To: "pgsql-performance (at) postgresql (dot) org" <pgsql-performance(at)postgresql(dot)org>
Subject: Re: Scaling further up
Date: 2004-03-03 08:57:18
Message-ID: 20040303085718.A24535@bacon
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On 02/03/2004 23:25 johnnnnnn wrote:
> [snip]
> random_page_cost should be set with the following things taken into
> account:
> - seek speed

Which is not exactly the same thing as spindle speed as it's a combination
of spindle speed and track-to-track speed. I think you'll find that a 15K
rpm disk, whilst it will probably have a lower seek time than a 10K rpm
disk, won't have a proportionately (i.e., 2/3rds) lower seek time.

> - likelihood of page to be cached in memory by the kernel

That's effective cache size.

--
Paul Thomas
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