[Beowulf] DC Power Dist. Yields 20%
hahn at physics.mcmaster.ca
Thu Aug 10 21:38:33 PDT 2006
> 20% is a lot, both in terms of consumption and cooling capacity. I'm
the article says "up to 15%" at the facility level - did you get 20%
by figuring a savings at the rack level, too?
afaikt, the article is based on an assumption that everything is powered
by an online UPS, and probably that node PSU's are low-performance (say,
65%). sometimes studies like this ignore fact that incoming power is
inherently AC (that is, only start looking at efficiency given DC supply.)
I'd love to see DC gain more traction - PSU's are certainly one of the
flakier components in our systems, though per node (HP DL145G2), they
only contain 2 of 14 fans (or of 18 moving parts). I don't know whether
there's a reason to think many small AC-DC PSU's would be less efficient
than a couple really big ones (factoring in the cost and inefficiency
of DC power distribution).
I'd certainly be interested in a distribution system (whether AC or DC)
that avoided so damn many plugs and sockets and breakers and PDUs.
I guess I'm more enthused about servers becoming lower-powered,
and also quite interested in better ways to dissipate the heat than
raised floors and traditional chillers...
> curious how long it would take before DC supplied racks become cost
well, there's already a standard DC supply - to the motherboard.
one impediment might be that it's got +12, -12, 5, 3.3 and probably
a couple others. if it were just a matter of providing lightly
regulated 12V, life would probably be a lot simpler. and I'm not
sure MB's would be much more complicated, either, since the current
main consumer, the CPU, already has a fairly flexible and high-power
onboard dc-dc converter. (I wonder how efficient it is, typically...)
regards, mark hahn.
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