Interesting People mailing list archives
IP: Re: computer and telecom centers get undeserved black eye for power usage
From: David Farber <dave () farber net>
Date: Mon, 09 Apr 2001 18:00:58 -0400
Date: Mon, 09 Apr 2001 07:24:04 -0700 To: farber () cis upenn edu, ip-sub-1 () majordomo pobox com From: "Joseph C. Pistritto" <jcp () jcphome com> Subject: Re: IP: computer and telecom centers get undeserved black eye for power usage I just got done ordering our data center setup at Zaplet Inc. where I used to work. The datacenter is at Equinix. We provisioned it at 2 20amp 120V circuits per rack (42U units of equipment). That's not enough for 42U of "1U" servers, but then you have a huge cooling problem as well if you dump that much power into that small a space. The reason we used 2 20amp circuits was for redundency, but i can see someone actually *using* that much power if they really fill up the rack space (in which case you'd need to provision additional circuits but not additional current draw for redundency). So assuming 20amps @ 120v = approx 2.5KW per "rack" and lets say it takes *another* 2.5KW to air condition that space (which is overkill, air conditioning is more efficient than resistive heating, which is essentially what computers are...), that means approximately a 4 sq. foot area would have 5KW of draw. (not including corridors and such). Or 2.5KW per square foot (high estimate). So that works out to: 1.25KW per sq. foot (high estimate for densely packed areas) We know this is high because people usually quote "available power" in the 200-300 watts/sq. foot range (inclusive of hallways etc.). 275watts/sq. ft. is a common metric used here for power availability for instance. (your lesser dataccenters dont even have that much available). (thats direct power draw, not including airconditioning, so doubling that would be approximately 0.5 KW/sq. ft. So we can tell my estimate above from our racks is high, but irrationally so for actual worst case). It seems reasonable that a datacenter (aka "server farm") would ask for 10 megawatts of power though. (so 46 of them could well have asked for 500 Megawatts). I know that *ONE* 2 million sq. ft planned facility in San Jose is speced at 190Megawatts (the city council is forcing them to put in a cogen plant with that capacity before building it though...) I think the 60-100KW/sq. ft. is an arithmetic error though. -jcp-
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- IP: Re: computer and telecom centers get undeserved black eye for power usage David Farber (Apr 09)
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- IP: Re: computer and telecom centers get undeserved black eye for power usage David Farber (Apr 09)