From: | "Luke Lonergan" <llonergan(at)greenplum(dot)com> |
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To: | "Stefan Kaltenbrunner" <stefan(at)kaltenbrunner(dot)cc> |
Cc: | "PostgreSQL-development" <pgsql-hackers(at)postgresql(dot)org> |
Subject: | Re: random observations while testing with a 1,8B row |
Date: | 2006-03-10 20:02:43 |
Message-ID: | C0371B63.1EF73%llonergan@greenplum.com |
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Stefan,
On 3/10/06 11:48 AM, "Stefan Kaltenbrunner" <stefan(at)kaltenbrunner(dot)cc> wrote:
> 2 HBAs in the server, 2x2 possible paths to each LUN.
> 6 disks for the WAL and 12 disks for the data
So - you have 18 disks worth of potential bandwidth, not factoring loss due
to RAID. That's roughly 18 * 60 = 1,080 MB/s. If we organized that into
four banks, one for each CPU and made each one RAID5 and left two disks for
spares, you'd have 12 disks working for you at 720MB/s, which is possibly
double the number of active FC channels you have, unless they are all
active, in which case you have a nicely matched 800MB/s of FC.
>> So, from 15 MB/s up to about 20 MB/s.
Gee - seems a long distance from 700 MB/s potential :-)
> the IO-System I use should be capable of doing that if pushed hard
> enough :-)
I would expect some 10x this if configured well.
> interesting to know, but still I'm testing/playing with postgresql here
> not bizgres MPP ...
Sure. Still, what I'd expect is something like 10x this update rate using
the parallelism buried in your hardware.
If you configure the same machine with 4 Bizgres MPP segments running on 4
LUNs I think you'd be shocked at the speedups.
- Luke
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