From: Tom Lane <tgl@sss.pgh.pa.us>
To: Luke Lonergan <llonergan@greenplum.com>
Cc: Alan Stange <stange@rentec.com>
Cc: Greg Stark <gsstark@mit.edu>
Cc: Dave Cramer <pg@fastcrypt.com>
Cc: Joshua Marsh <icub3d@gmail.com>
Cc: pgsql-performance@postgresql.org
Subject: Re: Hardware/OS recommendations for large databases (
Date: Mon, 21 Nov 2005 09:56:46 -0500
Message-ID: <1611.1132585006@sss.pgh.pa.us> (raw)
In-Reply-To: <BFA6C187.1425C%llonergan@greenplum.com>
References: <BFA6C187.1425C%llonergan@greenplum.com>
"Luke Lonergan" <llonergan@greenplum.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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To: pgsql-performance@postgresql.org
Cc: tgl@sss.pgh.pa.us, llonergan@greenplum.com, stange@rentec.com, gsstark@mit.edu, pg@fastcrypt.com, icub3d@gmail.com
Subject: Re: Hardware/OS recommendations for large databases (
In-Reply-To: <1611.1132585006@sss.pgh.pa.us>
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