From: | Alan Stange <stange(at)rentec(dot)com> |
---|---|
To: | Luke Lonergan <llonergan(at)greenplum(dot)com> |
Cc: | Dave Cramer <pg(at)fastcrypt(dot)com>, Greg Stark <gsstark(at)mit(dot)edu>, Joshua Marsh <icub3d(at)gmail(dot)com>, pgsql-performance(at)postgresql(dot)org |
Subject: | Re: Hardware/OS recommendations for large databases ( |
Date: | 2005-11-18 16:13:44 |
Message-ID: | 437DFDB8.1030208@rentec.com |
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Thread: | |
Lists: | pgsql-performance |
Luke Lonergan wrote:
> Alan,
>
> On 11/18/05 6:46 AM, "Alan Stange" <stange(at)rentec(dot)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
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