Re: WSJ: Big tech firms seeking power

[Alex Rubenstein <alex () nac net>]

> What is the amount of energy coming out of a server as heat as opposed to 
> what you put in as electricity? My guess would be pretty close to 100%, but 
> is it really so? And I've also been told that you need approx 1/3 of the 
> energy taken out thru cooling to cool it? So that would mean that to sustain 
> a 100W server you really need approx 130-140W of power when cooling is 
> included in the equation. Is this a correct assumption?

Based upon my real-world experience, and talking to a few folks, it's very 
close to 100%. Most assume 100% for the practice of calculating cooling.

However, for those who are very scientific, they try to tell you that some 
of the power is going into movement of hard drive heads, etc., which 
creates force on your racks, etc. A true, but irrelevant discussion, 
really, because it's likely an immeasurable amount.

One could do the excercise of putting a computer in a well insulated box 
and measuring power in vs. rate of rise of temperature. Volunteers? :)




--
Alex Rubenstein, AR97, K2AHR, alex () nac net, latency, Al Reuben
Net Access Corporation, 800-NET-ME-36, http://www.nac.net