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Re: Postgresql Performance on an HP DL385 and

From: "Steve Poe" <steve(dot)poe(at)gmail(dot)com>
To: "Luke Lonergan" <llonergan(at)greenplum(dot)com>
Cc: "Alex Turner" <armtuk(at)gmail(dot)com>, pgsql-performance(at)postgresql(dot)org
Subject: Re: Postgresql Performance on an HP DL385 and
Date: 2006-08-08 16:57:43
Message-ID: 721b21dc0608080957k166a7bc5t72cb3cf076e6da01@mail.gmail.com (view raw or flat)
Thread:
Lists: pgsql-performance
Luke,

Here's some background:
I use Pg 7.4.13 (I've tested as far back as 7.4.8). I use an 8GB data with a
program called odbc-bench. I run an 18 minute test. With each run, HP box
excluded, I unmount the discs involved, reformat, un-tar the backup of
PGDATA and pg_xlog back on the discs, start-up Postgresql, then run the
odbc-bench.

On the Sun box, I've benchmarked an average of 3 to 4 runs with each disc
(up to 8) in succession in RAID0, RAID5, and RAID10 where applicable. I've
done with with pg_xlog on the same discs as PGDATA and separately, so I've
felt like I had a good understanding of how the performance works. I've
notice performance seems to level off at around 6 discs with another 10-15%
with two more discs.

When I run odbc-bench, I also run vmstat in the background (through a python
script) which averages/summarzies the high/low/average of each category for
each minute then a final summary after the run.

On the Sun box, with 4 discs (RAID10) to one channel on the LSI RAID card, I
see an average TPS around 70. If I ran this off of one disc, I see an
average TPS of 32.

on the HP box, with 6-discs in RAID10 and 1 spare. I see a TPS of 34. I
don't have my vmstat reports with me, but I recall the CPU utilitization on
the HP was about 50% higher. I need to check on this.

Steve







On 8/8/06, Luke Lonergan <llonergan(at)greenplum(dot)com> wrote:
>
> Steve,
>
> On 8/8/06 8:01 AM, "Steve Poe" <steve(dot)poe(at)gmail(dot)com> wrote:
>
> > Thanks for the feedback.  I use the same database test that I've run a
> Sun
> > dual Opteron with 4Gb RAM and (2) four disk arrays in RAID10. The sun
> box with
> > one disc on an LSI MegaRAID 2-channel adapter outperforms this HP box. I
> > though I was doing something wrong or there is something wrong with the
> box.
>
> Given the circumstances (benchmarked I/O is great, comparable perf on
> another box with single disk is better), seems that one of:
> 1) something wrong with the CPU/memory on the box
> 2) something with the OS version / kernel
> 3) something with the postgres configuration
>
> Can you post the database benchmark results?
>
> - Luke
>
>
>

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