[Beowulf] The fan from hell

Eray Ozkural examachine at gmail.com
Fri Jun 10 12:13:49 PDT 2005

Hi David,

Are you certain that replacing the fans will solve your heat
problem in the long run? My parallel database code runs
continuously for >1day, up to 40 processors. In the end
we measured that the system consumed more energy
than what the cooling system consumed! When a friend arrived
the other day he found the system room at 45 celcius,
with hot steam in the air :) I don't know what the board
temperature was, but I'm sure they got pretty hot.
Luckily nothing broke down.


On 6/10/05, David Mathog <mathog at mendel.bio.caltech.edu> wrote:
> Today I distributed database fragments out from the main server
> to the 20 compute nodes.  This required the server to run gunzip
> pretty much continuously for a couple of hours. The net result of
> which was that CPU1's temperature rose from 55C to 60-61C.
> Normally the fan on CPU1 sits happily at 5033 RPM. However
> today it started to slow down.  In fact it slowed down below
> 3000RPM, which triggered an automatic shutdown of the server.
> After a bit of experimentation I've now determined that
> this wasn't a coincidence. This CPU fan really does run
> slower when the CPU gets hotter.  It takes a
> few minutes before it starts to slow down, but slow down it
> does.  Not exactly the desired response for a fan on a hot CPU!
> This is on an Athlon MP 2000+ processor and the fan is Dynatron
> model that AMD used with the boxed CPU.
> Any of the system vendors (or anybody else) out there have a
> preferred brand of 60mm fan that doesn't slow down at 60C?
> Thanks,
> David Mathog
> mathog at caltech.edu
> Manager, Sequence Analysis Facility, Biology Division, Caltech
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Eray Ozkural (exa), PhD candidate
Comp. Sci. Dept., Bilkent University, Ankara  KDE Project: http://www.kde.org
http://www.cs.bilkent.edu.tr/~erayo  Malfunction: http://www.malfunct.com

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