[Beowulf] Re: Setting up a new Beowulf cluster

David Mathog mathog at caltech.edu
Thu Feb 14 08:39:31 PST 2008

Jim Lux <James.P.Lux at jpl.nasa.gov> wrote:

> >>quiet down a rack because to first order sound insulation == heat
> >>insulation. \
> Actually, no.. good acoustic isolation is not good thermal 
> isolation.  Sure, things like fiberglass batts provide thermal 
> insulation and also (slightly) attenuate high frequencies.

I guess I should have used => or some other "implies".  Sound insulators
tend to be good heat insulators, heat insulators are generally not good
sound insulators.

I spent way too long trying to quiet down a rack when it had to live in
a classroom.  Mass loaded vinyl on all 4 sides worked fairly well
to stop the noise coming out that way, but then it just turned into a
big speaker enclosure and directed nearly as much sound out the fan
holes, where it bounced off the ceiling and floor.  And the rack exhaust
fans (2 very high capacity 120mm fans on the top) were not able to keep
it cool when it was fully sound insulated.  The rated capacity
of those two fans was more than the sum of all the little ones in the
nodes, but the air flow was too restricted, I think mostly by the narrow
space between the node's front panels and the front insulator panel.
Thankfully it finally moved to a machine room and the noise problem went

Anyway, it is a much easier to sound insulate a room than it is a single
noisy rack.

David Mathog
mathog at caltech.edu
Manager, Sequence Analysis Facility, Biology Division, Caltech

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