Measure and Accelerate Green in Your Data Center

For the most part, being green in the data center is about increasing power efficiency and thereby reducing greenhouse gas emissions. From a purely environmental and ecological perspective, higher levels of green could be achieved by examining the entire life cycle of technology systems— from production and supply chain all the way to the disposal of toxic components. But for now let’s stick with the power efficiency theme.

Here are some Green Grid developed metrics for evaluating data center facility efficiency:

• PUE—Power Usage Effectiveness represents how much total power you need to drive your IT systems when you take into account power distribution, cooling, humidification, lighting, etc. If you need 1MW to run your IT systems, a PUE of 1.8 means that you are consuming 1.8MW to get this usable level of power.
• DCiE—Data Center Infrastructure Efficiency represents the ratio of IT equipment power to total facility power. Using the same example, a facility with a PUE of 1.8 has a DCiE of about 55%, meaning a little more than half of the power used by the data center is making its way to the IT systems (no mystery here; DCiE is simply the inverse of PUE).

From a planning perspective, I’ve personally found PUE to be a more useful tool than DCiE because it gives you a simple multiplier you can use to estimate your increasing facility requirements as you add new servers, storage and the like. While PUEs generally fall into the 1.7 (more efficient) to 3.0 range (less efficient), I have seen PUEs approach 1.3 when a holistic, facility-wide approach is taken regarding power efficiency.

Keep in mind, the PUE and DCiE numbers tell you how efficiently your data center is operating from a power distribution and cooling perspective. They do not tell you how efficiently your IT group is delivering useful value per kW of total power consumed.

This is exactly what Green Grid is trying to do next: define ways to measure overall Data Center Productivity (DCP). That is, Green Grid is attempting to help you quantify how well the energy you’re using is being applied to useful work. Since this is very complicated and will vary by application and industry, the Grid is hoping to define useful “proxies” or indicators that can provide some normalized measurement and useful insight.

Here are some of the types of measurement proxies being considered by the Green Grid (read the Green Grid Proxy White Paper for more details):

• Server productivity.Because you need a greater number of older servers to get the job done, and because older servers consume a lot more electricity per instruction executed than newer ones, you could come up with a productivity measurement based on MCUPS (million compute units per second) per kW consumed by the data center (the more, the better). This, of course, ignores the value of stored data which may be considerable, or even required for regulatory compliance. However, it provides a measure worth consideration.
• Server utilization and virtualization. Running high-end servers at 20% capacity means they are being used inefficiently.The idea here is that running servers at higher utilization rates is good and a highly virtualized environment has the

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