[Beowulf] Earthquakes and raised floors...

David Kewley kewley at gps.caltech.edu
Mon Jan 9 03:16:13 PST 2006

On Sunday 08 January 2006 14:03, Robert G. Brown wrote:
> I've never heard anyone say they were particularly happy having to mess
> with cabling running under a raised floor (but have heard plenty of
> griping) but there may be ways of laying it out nowadays that are easy
> (easier) to manage.

We have:

* AC units & their air intake directly behind racks
* ceiling-ductwork cooling to front of racks
* under-raised-floor cooling to front of racks
* under-floor routing of chilled water, power, and a few random things
* overhead cable-tray routing of network (a very open tray, easy to use)

Power comes in the bottom-rear of the racks, and network comes in the 
top-rear.  We have nearly no top-bottom homogeneity of ambient temperature 
in the racks, due to the up-down airflow and the large area in the front of 
the racks that allows much mixing.  I say "nearly no" because the top 2-3 
1U machines *are* a few degrees C warmer, likely because of recirculated 
hot air *inside* the racks.

Mind you, we have all 42U occupied in the racks (20U of machines in the 
bottom & top, and 2U space in the middle with a blanking panel & a 1U GigE 
switch).  So the power supply & the homogeneity of ambient temperature are 

The net result? Power cabling, which is largely static, keeps out of the way 
under the floor.  Network cabling, which is more complicated and dynamic, 
is easily managed overhad (at least for a 6'4" tall person like me :).  
Cooling is quite uniform.  There is minimal risk of flooding affecting the 
computers.  I'm sure there are other good ways to do things; this way has 
worked quite well for us.

Granted, I *am* still a bit nervous about the raised floor & earthquakes.


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