I was idly sketching on the backs of envelopes while on the trains last week, and I came up with the following:
One 1U rack mount compute server consumes (give or take, according to my measurements) 2A and 200W
During a day, that machine will consume 24 * 200W = 4800W = 5kWh
My domestic electricity costs about $0.17/kWh (dividing the bottom line by the number of kWh burned). I pay a surcharge to encourage them to buy electricity from renewable producers, so that ought to be high. Call it $0.20, just to be on the high side of everything. This also makes the math really simple:
5kWh/day * $0.2/kWh = $1/day to run my standard 1U server.
Running servers (the 1U, one disk, models that I deal with) costs $1/day, $30/mo, $365/yr
Clusters are expensive – 100 nodes would cost $36,000 a year in electricity. My usual estimate is that it costs as much to dissipate the heat as it does to generate it. Throw in that much again for AC. You’re talking about a full time employee worth of power and cooling.
For the real amusement (since I’m turning into a green freak) one can turn kWh into BTU, to figure out how much of each of several fuels a notional 100 node cluster would burn:
5kWh / day * 365 days * 100 nodes = 3113MBtu
- 3,113,450 cubic feet of natural gas
- 259,454 pounds of coal
- 24,907 gallons of gasoline
- 20,756 gallons of fuel oil.
Just for giggles, one may also note that buying those 20,756 gallons of gasoline at current market prices would be a heck of a lot cheaper than buying the equivalent energy from the power company. You can buy a nice generator for $5,000.
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