Energy-Efficient DataCenter Designs

Remember those green aspirations you had? How you'd do your bit to save the planet by re-engineering your IT operations for power efficiency? Don't worry, no one else remembers, either. But the fact remains, most data centers are still power-sucking cost centers and represent an opportunity for IT to save the company some cash. A 2007 Environmental Protection Agency report states that about half of electrical costs in data centers goes to powering environmentals like lights, fans, and compressors. That jibes with what Paul Jacobson, principal of data center consultancy Reliable Resources, is seeing. He says organizations typically spend between 45% and 55% of annual electrical expenses on cooling their data centers, making them prime targets for optimization and cost reduction.

One of the conventional wisdoms is that DC power is more efficient than AC power because DC distribution goes through fewer conversions. A paper from Lawrence Berkeley National Laboratory shows that DC distribution systems are about 7% more efficient than "best in class" AC UPSs and 28% more efficient than AC distribution systems typically found in data centers. A task group of the Green Grid, an IT industry consortium that's looking to standardize on energy efficiency metrics, processes, and technologies, takes issue with parts of Lawrence Berkeley's study. The task force argues that well designed DC and AC systems using current technology can actually be within 5% to 7% efficiency of each other. Before you replace your existing power distribution plant, you can do other, less radical things to reduce power costs.

Dean Nelson, senior director of global data center services at eBay, says organizations built data centers "2N+1" to meet availability goals. "There wasn't a focus on the efficiencies of the data center because one second of downtime was a lot of money," Nelson says."If you put in a good, efficient design, you will save money. It's a no brainer." Building an efficient data center starts with collecting data and reporting on power and cooling usage on a minute, hourly, or daily basis. Collection of environmental data is still in its infancy, with few standards. In January, Cisco launched its Energywise partnership program with the goal of positioning Cisco Catalyst switches as data collection points, which would forward the data to a repository and control points, and in turn could turn off the switches via Power Over Ethernet ports. Cisco initially aimed Energywise at the LAN and not the data center, though a goal is to plug into building management systems to control lighting and air conditioning.

Syracuse University is building a new data center and its IT team will monitor power usage down to the individual plugs so that it can report on server and application consumption, says CIO Christopher Sedore. But he wants to go further. Syracuse makes extensive use of virtualization, and Sedore would like to be able to measure how much power an application is using, whether it's hosted on a physical or virtual machine.

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