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References: <cone.1267562557.293175.32557.1000@shelca>
	<alpine.DEB.2.00.1003021313310.5131@asgard.lang.hm>
Date: Tue, 2 Mar 2010 14:21:24 -0700
Message-ID: <dcc563d11003021321u64a90ef7ybaf9113fd3ec1c28@mail.gmail.com>
Subject: Re: 10K vs 15k rpm for analytics
From: Scott Marlowe <scott.marlowe@gmail.com>
To: david@lang.hm
Cc: Francisco Reyes <lists@stringsutils.com>,
	Pgsql performance <pgsql-performance@postgresql.org>
Content-Type: text/plain; charset=ISO-8859-1

On Tue, Mar 2, 2010 at 2:14 PM,  <david@lang.hm> wrote:
> On Tue, 2 Mar 2010, Francisco Reyes wrote:
>
>> Anyone has any experience doing analytics with postgres. In particular if
>> 10K rpm drives are good enough vs using 15K rpm, over 24 drives. Price
>> difference is $3,000.
>>
>> Rarely ever have more than 2 or 3 connections to the machine.
>>
>> So far from what I have seen throughput is more important than TPS for the
>> queries we do. Usually we end up doing sequential scans to do
>> summaries/aggregates.
>
> With sequential scans you may be better off with the large SATA drives as
> they fit more data per track and so give great sequential read rates.

True, I just looked at the Hitachi 7200 RPM 2TB Ultrastar and it lists
and average throughput of 134 Megabytes/second which is quite good.
While seek time is about double that of a 15krpm drive, short stroking
can lower that quite a bit.  Latency is still 2x as much, but there's
not much to do about that.