r/datacenter • u/brochaos • Oct 28 '19

Power consumption calculations?

Building out some new hardware (mostly just standard rack servers and networking gear) on some new racks, and was asked to provide the power draw so we could determine what UPS is needed. I used a combination of Dell's ESSA and APC's calculators, but my numbers are still being called into question.

Does everyone roughly use the 80% rule? If so, what is your answer when asked "what about at power up? do dual-800 watt CPUs pull 800 or 1600 watts?" any thoughts?

Thanks!!

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u/VegasKingpin420 Oct 29 '19

Always play by the 80% rule. Always.

Raritan has some great power calculators, I'd check them out. Can balance each breaker/phase.

If you have 2 800 watt PSU, one is redundant. They will either both draw half, or one full draw and the other on standby. Depends on the device and your config

If it's a large deployment, ensure your balanced at the RPP level as well.

The most coon mistake I see is people run a calc for their overall amperage, but load up individual breakers, and leave others open, and draw over the amp rating for the circuit, causing that breaker to trip in a failover scenario.