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Subject: Re: Problems benchmarking postfix...
From: Brad Knowles (blkskynet.be)
Date: Sat Jun 03 2000 - 01:19:24 CDT

At 12:52 PM -0400 2000/6/2, scott wrote:

> These errors and the rest of your message indicate to me that most
> likely you need to tune the underlying OS settings such as NMBCLUSTERS
> and max files, etc (generally set under MAXUSERS) in the kernel
> configuration for the machine.

        Ahh, right. I forgot that I haven't installed a customized
kernel yet on this machine. Good point. I've got a pretty standard
one that I'm using elsewhere (on other news servers), and I'll bring
it over.

> I'm curious to know how the vinum striping affects performance, as
> we've tried similar tests and have yet to have come up with a vinum
> configuration that works well.

        I've finally got one on our news spool server that works pretty
well. It's attached to a Comparex/Hitachi drive array that does
RAID-5 reasonably well (we tried everything else, and nothing is
faster than RAID-5, and everything else has more issues than RAID-5),
but it can't create compound logical units, nor can it intelligently
handle more than five drives in a single LU.

        So, I have it export four RAID-5 LUs of five 18GB Seagate
"Cheetah" drives each, and then I stripe across those LUs in software
with vinum. I've gotten it to the point where I'm getting more than
5000 random read I/O operations per second, with average transfer
sizes of one sector.

        I reported on this configuration in news.software.nntp a while
back. I'd recommend searching on Deja.com to see if you can find
that article, which compares the performance I'm getting with what
Joe Greco is getting on his much larger vinum configuration, and what
another guy is getting with his solid-state disk. 

--
   These are my opinions -- not to be taken as official Skynet policy
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Brad Knowles, <blkskynet.be>                || Belgacom Skynet SA/NV
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http://www.skynet.be                         || Belgium