http://www.eweek.com/article2/0,1759,2000867,00.asp
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
effective.
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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