Data Centre Specialist Group

As more pressure is applied to the Data Centre market to become more efficient, Data Centre operators will soon be targeted, measured, grouped or labelled by the efficiency of their facility. Many streams are currently underway in both the European Union and United States to develop and apply such metrics. The BCS Data Centre Specialist Group has been investigating efficiency, models and metrics for some time, the members release of the Data Centre Energy Efficiency Metrics paper here presents our recommendations to operators and Code of Conduct authors on the first stage metrics, both reporting and analytical.

The purpose of the Data Centre should not be overlooked when discussing metrics, much of the discussion of metrics and targets so far has focussed upon the Data Centre infrastructure as if that was an end goal in itself. The purpose of a data centre is to house the IT equipment whose purpose is to deliver IT services to business users or customers. Therefore the energy efficiency of the Infrastructure (PUE / DCiE etc) is not and never will be a measure of 'how efficient is my data centre' as it contains no information about the efficiency of the IT equipment, systems architecture or applications.

End to end metrics are an obvious end goal for any metrics development work stream and the capability to form part of a holistic set of metrics is a critical consideration for these infrastructure metrics. The DCSG believes that to make real progress any data centre efficiency metric will need to be part of a measurement methodology designed to calculate a reasonable and fair approximation of the total environmental and financial cost of the service provision from the data centre.

The metrics presented to date by the Green Grid (PUE , DCiE) and others are critically flawed in this regard. Whilst they are effective reporting metrics for senior management and possibly for targeting they are not reversible and will never be able to form part of a methodology to calculate the total cost of provisioning a service from a data centre. These metrics also vary with the IT electrical load in the facility and are unable to determine either the financial or environmental benefits of changes to IT equipment within the facility.

In this paper the DCSG set out companion analytical metrics to the DCiE reporting metric that are  derived from the same facility measurements and allow the operator to understand the performance of their facility, predict and understand the impacts of changes to infrastructure, process or IT equipment, build business cases for green programs and forecast the DCiE after such changes.