North American Network Operators Group

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RE: rack power question

  • From: Jon Lewis
  • Date: Sun Mar 23 13:37:19 2008

On Sun, 23 Mar 2008, Ray Burkholder wrote:

My desktop has a 680 Watt power supply, but according to a meter I once
connected, it is only running at 350 to 400 Watts.  So if a server has a
980W power supply, does the rack power need to be designed to handle
multiples of such a beast, even though the server may not come close
(because it may not be fully loaded with drives or whatever)?  Wouldn't it
be better to do actual measurements to see the real draw might be?

This depends on who's providing the power. If it's your power and your servers, you can "know" that your 980W supplies are really only using 600W, be happy, and plan accordingly if you upgrade later.

If you're providing the power, but it's someone else's gear, you better have good communication when it comes to power requirements/utilization, because what happens when they install more drives/processors next month, and those systems that were using 600W suddenly are using 800W each?

When providing/planning UPS power, if you sell a 120V 20A circuit, do you budget 120V 20A of UPS power for that customer, or 16A (80%), or even slightly more than 20A (figuring worst case, they're going to overload their circuit at some point) when deciding how full that UPS is?

 Jon Lewis                   |  I route
 Senior Network Engineer     |  therefore you are
 Atlantic Net                |
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