[Beowulf] 512 nodes Myrinet cluster Challanges

[Joe Landman]

Mark Hahn wrote:

> in the cluster above, I choose a chassis (AIC) which has a large centrifugal
> blower, rather than a bunch of 40mm axial/muffin fans.  a much larger cluster
> I'm working on now (768 nodes) has 14 40mm muffin fans in each node!  while
> I know I can rely on the vendor (HP) to replace failures promptly and without
> complaint, there's an interesting side-effect: power dissipation.  of 12 fans
> pointing at the CPUs are actually paired inline, and each pair is rated to 
> dissipate up to 20W.  so a node that idles at 210W and 265W under full load
> can easily consume 340W if the fans are ramped up.  ouch!

Heh... Load up a Sun v20z with a CPU pounding calculation, and as the 
CPUs heat up, they wind the fans up.  I had several parallel GAMESS runs 
going and it reminded me of a turbo pump winding up ....  Its neat to 
probe the hardware status and see the fans wind up from 4-5000 RPM 
through 12kRPM ...



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Joseph Landman, Ph.D
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