– Larry Vertal, the Executive Director of The Green Grid (www.thegreengrid.org), says:
The release by The Green Grid of PUE & DCiE, which have become common measures used globally, certainly showed the pent up demand for metrics that were not self-serving marketing tools!
While The Green Grid defined the metrics carefully, provided the guidance on usage in straightforward whitepapers, released a tool to assure consistent reporting there are still claims of confusion.
While these initial metrics by TGG were intended to enable continuous improvement of a given data center, some of the stir and alleged confusion lies in desire to use the metrics to compare one data center to another. For example comparing a web page hosting data center with one focused on financial transactions that have different design points and requirements. In our competitive industry the desire to use any metrics for marketing initiatives is understandable and in the heat of competitiveness can lead to misuse and drive confusion.
I would suggest that real rather than alleged confusion in many cases comes from the fact that many folks have heard about PUE but have not been able to take the time to read the short and straightforward whitepapers of TGG defining and guidance on implementation. It is like the old children’s “telephone game” where the actual meaning and message get muddled at each step of discussion by secondary and tertiary sources. It is understandable especially with small and medium sized IT departments who often time depend on third parties for information and feel that they do not have time to go to the source but in reality the source documents in this case are quick reads!
Without taking the first steps to measurement you are unable to measure the affect you have when you implement changes or indeed do planning which is more than “dart throwing”. However, it should not be so. The Green Grid defined PUE usage so it could be implemented at different levels of precision and measuring at the least precise level can give small and midsize data centers valuable information to control their destiny. At Level-1 the operator merely measures facility power at one point, the overall power going into the facility, measures the IT power used via UPS output and does the measurements monthly or weekly.
What’s a key goal? Not just on one hand how much energy is being used or on the other hand how much real work of value is being done but the combination of the two: Productivity. And measured in a manner that is do-able, of value and cannot be “gamed.” This is not easy.
The Green Grid Data Center Energy Productivity (DCeP) metric is very complete, very accurate and one of the US National Laboratories, PNNL, has worked with The Green Grid and published results that prove its validity. However because of its accuracy it can require a level of instrumentation that is a barrier to most data centers in implementation today. As the level of data center instrumentation evolves and improves generally The Green Gird is approaching this issue in two key ways. We have begun work in testing self-reporting data center applications which report out real work which when combined with power and energy measurements allow real insight.
Additionally we are involved in evaluation with the industry and end users of Proxies that may be used for energy-based productivity estimates. These include such proxies as those based on DCeP sample workloads, bits per KWH and CPU-utilization such as SPECint_rate, SPECpower and CUPS.
While DCeP is the general solution and self-instrumented applications will take time for development and deployment by vendors and users, the interim approach with Proxies is underway. Use of the proxy approach has the potential to help small and midsize data centers in particular by having low barrier to implementation.
