Is the Power Usage Effectiveness (PUE) metric the best way to measure data center efficiency?
I'm not the first one to ask that question, and I probably won't be the last. However, it does seem that IT executives are growing overly comfortable with PUE at a time when a growing chorus of voices are warning against its enshrinement as the standard for energy use.
At the moment, the EPA is firmly in PUE's corner. The agency is on the verge of releasing a Portfolio Manager tool that will be used to gauge individual data centers' qualifications under the Energy Star program. It's the same system used to track use at banks, hospitals, offices and other commercial buildings, and it uses PUE as its guiding principal.
The problem, according to critics, is that PUE calculates efficiency as a ratio between total consumption and consumption of strictly IT-related equipment -- a lower number indicating greater efficiency. It does not take into consideration overall data loads, system performance factors or other measurements to indicate energy consumed as related to the amount of data being processed or the speed at which it does so. It also does not factor in cooling requirements for IT equipment, allowing data centers in colder climates to achieve lower PUE ratings than those in warmer areas.
more of the IT Business Edge article from Arthur Cole