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Re: Hardware/OS recommendations for large databases (

From: Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>
To: "Luke Lonergan" <llonergan(at)greenplum(dot)com>
Cc: "Alan Stange" <stange(at)rentec(dot)com>, "Greg Stark" <gsstark(at)mit(dot)edu>, "Dave Cramer" <pg(at)fastcrypt(dot)com>, "Joshua Marsh" <icub3d(at)gmail(dot)com>, pgsql-performance(at)postgresql(dot)org
Subject: Re: Hardware/OS recommendations for large databases (
Date: 2005-11-21 14:56:46
Message-ID: 1611.1132585006@sss.pgh.pa.us (view raw or flat)
Thread:
Lists: pgsql-performance
"Luke Lonergan" <llonergan(at)greenplum(dot)com> writes:
> OK - slower this time:

> We've seen between 110MB/s and 120MB/s on a wide variety of fast CPU
> machines with fast I/O subsystems that can sustain 250MB/s+ using dd, but
> which all are capped at 120MB/s when doing sequential scans with different
> versions of Postgres.

Luke, sometime it would be nice if you would post your raw evidence
and let other people do their own analysis.  I for one have gotten
tired of reading sweeping generalizations unbacked by any data.

I find the notion of a magic 120MB/s barrier, independent of either
CPU or disk speed, to be pretty dubious to say the least.  I would
like to know exactly what the "wide variety" of data points you
haven't shown us are.

			regards, tom lane

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