Measuring power

Adrian Lai perl at
Wed Apr 29 10:16:26 BST 2009

2009/4/29 Andrew Beattie <andrew at>:
> This is a long way off topic but I'm hoping that someone here might be able
> to share a clue...
> I need to measure the power used on dozens and dozens of servers.
> I need a breakdown by server, not a total for the room.
> (more specifically, I want to calculate the power cost per server per year).
> Added difficulty:  I want to do this non-intrusively.
> I can't go round, yanking out cables and inserting in-line meters.
> So, I got a clamp meter.  But contrary to my expectation, that only works if
> I can separate the individual wires in the power cable - not an option.
> So, I'm stuck.  Is there any non-intrusive way to measure the power
> consumption of my servers?
> Andrew

Do you need exact figures?

And, by non-intrusively, do you mean from a software point of view as well?
I'm thinking a utility like powertop could be of use, although I'm not
sure how well that would compare with losses in the PSU and fans and
Presumably you could use an in-line meter for one server, and use this
to work out a best guess for others.


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