Green Channel

APC founder and CTO Neil Rasmussen was in London recently to talk about datacentres, power and efficiency - themes that have become headline news as they transmogrify into green issues. We took the opportunity to ask him - inter alia - whether the datacentre can ever be green.

Energy efficiency has become an important issue - if not the most important issue - in the datacentre. Given datacentre managers' reliance on hardware vendors, how much difference can they really make?

Our research shows that many of the electrical inefficiencies of datacentres are caused by installation and operating practices rather than by the power and cooling equipment itself. Therefore, there are definitely actions that datacentre operators can take to improve efficiency, particularly related to cooling. Examples where user action can improve efficiency include location and orientation of IT equipment, location of air vents, use of blanking panels, air conditioner temperature and humidity settings, and others. APC-MGE has a variety of white papers providing additional information, and an engineering staff that can help users get started.

You argue that datacentre managers need to be able to measure the efficiency of their datacentre. What are the first steps along this road?

We expect that datacentres of the future will be instrumented for electrical efficiency as a standard practice. Unfortunately, at this time almost no datacentres are correctly instrumented for efficiency - and most are not instrumented for efficiency at all. For existing datacentres, managers need to engage professionals to perform a datacentre efficiency audit to get started. Due to the specialised nature of datacentre power and cooling, specialists should be engaged - a typical building efficiency audit is not sufficient to guide datacentre efficiency improvement.

What are the key metrics for measuring datacentre efficiency?

The EC and the US EPA are in agreement on the need for two metrics - one for the electrical efficiency of power and cooling infrastructure, and another for useful IT work per watt. The electrical efficiency metric is called "Data Centre Infrastructure Efficiency," or DCiE, and is now well defined. The industry is still working to define "useful IT work per watt."

What is the minimum number of measurements a datacentre manager needs?

Ideally, datacentres in the future will be instrumented at the outset for efficiency, and will require no special measurements. But today, specialised measurements must be made to determine electrical efficiency. You can compute power and cooling efficiency with just a few power measurements, but understanding your inefficiencies well enough to create an efficiency improvement plan can require dozens of measurements. The number of measurements varies depending on the size and design of the datacentre.

To what extent can datacentre managers rely on vendors' power ratings?

Historically, IT equipment power ratings have differed widely and inconsistently from the actual power draws. However, this is changing today, particularly for enterprise servers, storage, and routers; in these cases manufacturers often provide calculators or spreadsheets that help users determine IT power draws with high accuracy.

Datacentre managers come in two flavours: one manages the enterprise datacentre, the other is managing a datacentre containing other companies' systems. How do their energy-efficiency problems and solutions differ, in a practical, real-world sense?

The improvement of electrical and IT efficiency depends on creating and enforcing standards - standards for location and orientation of IT equipment, standards for maximum rack power, establishing and enforcing density zones, etc. This becomes much more difficult in a co-location type environment. Difficulty aside, in either case the datacentre manager who is empowered by accurate measurement and standardised procedures will be able to operate at higher electrical efficiencies.