# Understanding colo pricing with respect to power needs

I run a small shared web hosting company and rent all my servers.

I periodically consider switching to colocating my own boxen and inevitably get stuck understanding how much it may cost.

As far as I understand it you pay for space, bandwidth and power. Space and bandwidth are straightforward but power is a bit of a mystery to me.

Considering just a 1U single-server scenario (for simplicity's sake), one may generally have the option of 0.5A, 1A, 2A and so on.

I have no real clue how much power I'd need.

If I went for 0.5A, what sort of spec machine would that allow and under what (very general) usage conditions? Likewise for 1A, 2A and so on.

I appreciate that when considering what can be run on 0.5A there are a range of variables to consider, but all I'm looking for are rough ballpark figures.

What could I run on 0.5A? What example specs would be fine on 0.5A? What wouldn't be fine on 0.5A?

Feel free to throw in suggestions applicable to 1A, 2A or any other power level. I'm just trying to get a grasp of what can and can't be done with respect to typical power levels.

take a look at hardware vendor specs. dell for instance has nice online power calculator. it calculates btu / wats / amps for given setup [ you configure type of box, number of cpus, memory size and hdds ]. it even lets you assume low/high load.

even if you dont use dell hardware that calculator can give you a hint how much power disks/cpus/memories consume.

i assume ~1A per server with dual psu, dual quad core [ regular xeon e54xx ~2.5GHz, not low voltage], two hard drives, 4x 2GB ram. ymmv.

edit: ~1A @ 220V.

• That 1A number seems pretty low. I measured a rackable with a pair of opteron 250 CPUs and 8gb of ram in it -- under load 2.5A/110v. I took out one of the CPUs (and 4gb of ram) and the power draw went down to 1.2A. – chris Jul 17 '09 at 13:56
• @chris interesting. i've just checked 2x quad E5430@2.66GHz, 6x 500gb sata, dual psu, 16gb ram and saw 1.2A......ha now i see. i quietly assumed 220V. – pQd Jul 17 '09 at 14:17
• Yeah, it's much better to talk in watts everywhere, as that's independent of supply voltage. – womble Jul 17 '09 at 23:20

I've also see colo when I was pricing them that actually had a meter on every customer's plugs, so you paid for what you used, based on whatever Kwh rate they were billing at.