Long-term PUE

To calculate PUE a set of point-in-time measurements of the power consumed by the data centre and IT equipment is required. As such a single set of power measurements enabling PUE calculation may be affected by many different factors. Therefore it is important to understand how and when the TFP and ITEP measurements are taken.

A key factor affecting the PUE is the amount of processing that occurs in the workload at any one time. Measurements taken under different processing loads on the same day may be significantly different and as such will create confusion when analysing the PUE.

This may also be true of measurements taken at the same time on different days, as processing loads may vary by day, week, or other business cycle. PUE is recommended as a long-term review metric and strategic tool to observe performance in managing the efficiency of a data centre.

Manage Long Term PUE with Assessor

Therefore to adopt a valid and effective strategy for PUE, proven operational processes must be in place to collect, collate and analyse the data over time. These processes must further ensure that any changes in configuration, including hardware, software and operational activities, are aligned to any changes in the PUE.

With all the hype surrounding PUE, you could be forgiven for thinking it is the panacea of metrics for data centre energy efficiency. Unfortunately, it is not that simple. In the next section, we'll take a look at PUE's strengths and weaknesses and what affects them to determine what it really tells you about your data centre's efficiency.