Message-ID: <437DFDB8.1030208@rentec.com>
Date: Fri, 18 Nov 2005 11:13:44 -0500
From: Alan Stange <stange@rentec.com>
Reply-To: stange@rentec.com
Organization: Renaissance Technologies Corp.
User-Agent: Thunderbird 1.5 (X11/20051025)
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To: Luke Lonergan <llonergan@greenplum.com>
CC: Dave Cramer <pg@fastcrypt.com>, Greg Stark <gsstark@mit.edu>,
	Joshua Marsh <icub3d@gmail.com>, pgsql-performance@postgresql.org
Subject: Re: Hardware/OS recommendations for large databases (
References: <BFA332EE.14035%llonergan@greenplum.com>
In-Reply-To: <BFA332EE.14035%llonergan@greenplum.com>
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Luke Lonergan wrote:
> Alan,
>
> On 11/18/05 6:46 AM, "Alan Stange" <stange@rentec.com> wrote:
>
>     That's 3 hours under load, with 80 compute clients beating on the
>     database at the same time. We have the stats turned way up, so the
>     analyze tends to read a big chunk of the tables a second time as
>     well. We typically don't have three hours a day of idle time.
>
>
> So I guess you’re saying you don’t know what your I/O rate is?
No, I'm say *you* don't know what my IO rate is.

I told you in my initial post that I was observing numbers in excess of 
what you claiming, but you seemed to think I didn't know how to measure 
an IO rate.

I should note too that our system uses about 20% of a single cpu when 
performing a table scan at >100MB/s of IO. I think you claimed the 
system would be cpu bound at this low IO rate.

Cheers,

-- Alan