[Beowulf] Quiet *and* powerful

Jim Lux James.P.Lux at jpl.nasa.gov
Fri Dec 12 17:48:26 EST 2003


First question... does it "really" need to be in the same room?

There is a huge variation in fan noise among models and makes of fan, and, 
furthermore, the structural stuff around it has an effect.  Perhaps just 
buying quieter fans and retrofitting?

Can you put the whole thing in a BIG sound isolated box (read, rack)... 
most equipment racks aren't designed for good acoustical properties.  There 
are, however, industries which are noise level sensitive (sound recording 
and mixing), and they have standard 19" racks, but with better 
design/packaging/etc.

If you're not hugely cost constrained, you can do away with fans entirely 
and sink the whole thing into a tank of fluorinert (but, at $70+/gallon....)

The other thing to think about is whether many smaller/lower power nodes 
can do your job.   If things scaled exactly as processor speed (don't we 
wish).. you've got 12 * 2.4 GHz = 28.8 GHz... Could 40 or 50 1GHz VIA type 
fanless processors work?

Overall, your best bet might be to get some custom sheet metal made to 
mount your motherboards in a more congenial (acoustic and thermal) 
environment.  Rather than have 2 layers of metal between each mobo, make a 
custom enclosure that stacks the boards a few inches apart, and which 
shares a couple big, but quiet, fans to push air through it.

In general, for a given amount of air moved, small fans are much less 
efficient and more noisy than big fans. (efficiency and noise are not very 
well correlated... the mechanical power in the noise is vanishingly small).



At 12:08 PM 12/12/2003 -0500, Joshua Baker-LePain wrote:
>Yes, I know this has been discussed a couple of times, and that my stated
>goals are at odds with each other.  But I really need the best bang for
>the noise for a system that will reside in the same room with patients
>undergoing diagnostic ultrasound scanning.  Our current setup (6 1U dual
>2.4GHz Xeons, with about 11 little fans per node) is ridiculously loud,
>and annoys both the patients and the physicians.  This is Bad.
>
>We're willing to pay for better, but don't want to take too much of a
>speed hit.  Does anybody have a good vendor for quiet but still high
>performing systems?  Is there any hope in the 1U form factor (my Opteron
>nodes are somewhat quieter, since they use squirrel cage fans, but are
>still too loud), or should I look at, e.g., putting Quad Opterons in a 3
>or 4U case?  Or should I look at lashing together some towers (this system
>also needs to be somewhat portable)?
>
>Thanks for any hints, pointers, recommendations, or flames.
>
>--
>Joshua Baker-LePain
>Department of Biomedical Engineering
>Duke University
>
>
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James Lux, P.E.
Spacecraft Telecommunications Section
Jet Propulsion Laboratory, Mail Stop 161-213
4800 Oak Grove Drive
Pasadena CA 91109
tel: (818)354-2075
fax: (818)393-6875

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