User-Agent: Microsoft-Entourage/11.2.1.051004
Date: Fri, 18 Nov 2005 09:54:07 -0800
Subject: Re: Hardware/OS recommendations for large databases (
From: "Luke Lonergan" <llonergan@greenplum.com>
To: stange@rentec.com
cc: "Dave Cramer" <pg@fastcrypt.com>, "Greg Stark" <gsstark@mit.edu>,
	"Joshua Marsh" <icub3d@gmail.com>, pgsql-performance@postgresql.org
Message-ID: <BFA3553F.1406D%llonergan@greenplum.com>
Thread-Topic: [PERFORM] Hardware/OS recommendations for large databases
 (
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In-Reply-To: <437E0FF5.5090203@rentec.com>
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Alan,

On 11/18/05 9:31 AM, "Alan Stange" <stange@rentec.com> wrote:

> Here's the output from one iteration of iostat -k 60 while the box is
> doing a select count(1) on a 238GB table.
> 
> avg-cpu:  %user   %nice    %sys %iowait   %idle
>            0.99    0.00   17.97   32.40   48.64
> 
> Device:            tps    kB_read/s    kB_wrtn/s    kB_read    kB_wrtn
> sdd             345.95    130732.53         0.00    7843952          0
> 
> We're reading 130MB/s for a full minute.  About 20% of a single cpu was
> being used.   The remainder being idle.

Cool - thanks for the results.  Is that % of one CPU, or of 2?  Was the
system otherwise idle?
 
> We've done nothing fancy and achieved results you claim shouldn't be
> possible.  This is a system that was re-installed yesterday, no tuning
> was done to the file systems, kernel or storage array.

Are you happy with 130MB/s?  How much did you pay for that?  Is it more than
$2,000, or double my 2003 PC?
 
> What am I doing wrong?
> 
> 9 years ago I co-designed a petabyte data store with a goal of 1GB/s IO
> (for a DOE lab).   And now I don't know what I'm doing,

Cool.  Would that be Sandia?

We routinely sustain 2,000 MB/s from disk on 16x 2003 era machines on
complex queries.

- Luke