[Beowulf] clustering using off the shelf systems in a fish tank full of oil.

Lux, Jim (337C) james.p.lux at jpl.nasa.gov
Wed Dec 28 10:51:03 PST 2011

On 12/28/11 10:06 AM, "Jonathan Aquilina" <eagles051387 at gmail.com> wrote:

>On 12/28/2011 11:30 AM, Lux, Jim (337C) wrote:
>> And you'll have your oily floor "service depot" somewhere else...  (and
>> you'll still have oily floors under your racks.. Oil WILL move through
>> wires by capillary attraction and/or thermal/atmospheric pumping.
>> experiment:  Get a piece of stranded wire about 30 cm long.  Fill a cup
>> glass with oil to within a couple cm of the top.  Drape the wire over
>> edge of the cup with one end in the oil and the other end on a piece of
>> paper on the surface of the table. (do all this within a raised edge pan
>> or cookie sheet).  Wait a day or two.  Observe.  Clean up.
>Wait a min guys maybe i wasnt clear, im not saying using standard server
>cases here. I am talking about actually using fish tanks instead. would
>you still have that leaking issue?

Almost certainly.  Unless you arrange for all the wires to end up higher
than the surface of the oil, the tube formed by the insulation serves as a
nice siphon, started by capillary effects, to drain your tank on to the
floor. (Faraday mentioned this effect with the shaving towel over the edge
of the basin). 

And "open container of oil" (your fishtank) works for the short run, but
you have to figure out how to keep it clean, while still vented, and keep
moisture out (you're not insulating for HV, so that's not a big problem,
but moisture in the oil will wind up in places where it might cause
corrosion.. Running a bit warm helps "boil off" the water.

Works great as a demo, not so hot for the long term.

Try the experiment with the wire and glass of oil (use cheap cooking oil
or motor oil...).  Or to be fancy, how about a cluster of arduinos?

BUT, if you do go oil.. Shell Diala AX is probably what you want (or the
Univolt 65 equivalent).  Runs about $5-10/gallon in a 5 gallon pail,
cheaper in drums or truckload lots ($2-3/gallon, like most other
non-exotic industrial liquids)   You might find gallons of USP mineral oil
at a feed store (used as a laxative for farm animals) at a competitive
price, and for this application, the water content isn't as important, and
it probably won't spoil too fast.


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