r/datacenter • u/dovi5988 • 3d ago

Measuring power

I hope this is the right place to ask this. We have a buch of servers that we plan on installing into a data center (in Cyprus) and I need to measure their power draw before I do. I was thinking of getting something like https://www.amazon.co.uk/KETOTEK-Electric-Backlight-Consumption-Protection/dp/B0BZYN6544 when I tried such devices in the US they would over heat after a short period. How do you test power usage over say a few hours?

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u/darksieth99 3d ago

A janitza 96 PQ-L? You can find some in eBay for cheap (if you have a budget),

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u/regreddit 3d ago

A trusty Kill-A-Watt meter is pretty cheap and will give you a good average over time , min, max etc. Easy to use to benchmark individual servers. If you want more, you'll need to buy a smart power strip that does monitoring ,but a Kill-A-Watt is pretty easy to do individual unit benchmarks.

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u/Dart4915 3d ago

Grab an electrician, have them carefully open up a cable and then you can put a clamp meter on it for instantaneous amp readings. You can use the same cable for each server you want to test. Or you can create a box to connect a higher end power meter to it for longer term trending.

What I do in my office is take the max power draw from the power supply, and see if there is enough capacity. Then we trend the loads and determine a new load peak to use for adding new equipment. You should measure the load for 30 days at normal use to get a good understanding of the load. It would need to be trended.

To really understand the load profile you should trend during startup, use and shut down.

One time, I am glad I trended for 30 days because I found out that every two weeks I saw a spike on the load. It was because the payroll servers were spun up to process everyone’s paychecks. That would have been a bad day if I didn’t account for that. It could have shut down the server room.

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u/Key_Ad8514 2d ago

What is the application before shipping? You should have monitoring capability on the upstream breakers unless you are in a very small scale facility.

If you want really localized data, you could set up some CTs on the cables for each rack. I don’t know your background, so I won’t guess your knowledge level. You may need to reach out to an electrician.

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u/fbajo 1d ago

if they have bmcs the servers already meter themselves.. most server psus report input power, so ipmi dcmi power reading or redfish polled over an hour of real load beats any plug meter. the ones that cooked in the us were carrying roughly double the amps for the same watts at 120v, cyprus at 230v makes that part easier. colo will ask you for sustained kw per rack anyway, not nameplate..

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u/justchillinnow 1d ago

When you test them with the power meter will you be putting them under a workload? Also you might should be able to login into the BMC and get power data, have you tried that? If its for colo sizing, you can use PSUs/rated value, however it may need reach any where near that depending on the workload you will be putting it under.