Re: Deathly slow performance on SMP red-hat system

["Florian G. Pflug" <fgp(at)phlo(dot)org>]

Patrick TJ McPhee wrote:
> I have a Red Hat ELsmp system running on a dual opteron hp server with
> 16 gigs of memory. I believe the RH installation is straight out of the
> box. I've compiled postgres 8.1.4 from sources.
>
> The problem is that query performance is horrible, and I can't think
> why, although it seems clear the problem is outside the query engine.
> For instance, "select 1" takes on the order of 100ms. Explain analyze
> doesn't shed much light on why this might be:
I've had this problem on a old version of redhat. It turned out that
the driver included with redhat for the raid-controller was very slow -
i think that it was fsync-performance which was really bad with that driver.
The controller was as adaptec aacraid - in the end, we used debian, and
a recent 2.6 kernel, and things were much faster.

greetings, Florian Pflug