Mar 26, 2007

The Most Energy-Efficient Server Is One That's Powered Off

"Green data centers" and energy-efficient servers are the latest buzz in IT and government, as it turns out. Information Week's March 12 features green data center technologies as the cover storr. The online version doesn't have the same catchy Gordon Gecko-esque "Green is Good" title, but it's still a good read.

Today's data centers are built like offshore platforms from the oil and gas industry. Every 100 years, there's a monster wave, usually 50 feet high, from a massive hurricane or storm. So, offshore platforms are built to withstand this 100-year wave. The platform is taller than the wave's crest, and the platform is built to withstand the force of the wave.

Data centers are typically provisioned to meet peak demand, much the same way as oil platforms are engineered for that 100-year wave. Servers are provisioned to handle peak applications loads or traffic from major events, such as the quarterly sales promotion or special news event. On a typical day, however, utilization is much lower, but you still have all of those servers humming away, using electricity and generating heat.

What if you could power off all of those unused servers? Not only would you save electricity, you would also reduce your cooling costs. Could you determine which servers are idle and then those shut down? And could you do this automatically? How fast could you respond to changes in your environment? If load increases, could you power on the additional servers you need?

These are tough demands for your data center, but these changes can reduce your energy costs. The local utility, PG&E, is providing rebates to companies who can reduce their overall energy consumption or reduce their energy consumption on-demand in order to prevent rolling black-outs. We're participating in a new initiative by the Silicon Valley Leadership Group for energy-efficient data centers. As part of this initiative, we're showing how Cassatt Collage can be used to implement these use cases to reduce your overall power costs.

Back on the home front, we have several hundred servers in our system test lab. Since they're managed by Collage, only a third of the servers are usually powered on at a given time. When we do large scale-out tests, Collage fires up most of the servers in the lab. However, we usually schedule those scale-out tests for the weekends. Our lab A/C consists of three different units, each of which turn on when there is demand. One unit is constantly running; the second one kicks in during parts of the day; the third one only kicks in during heat waves or scale-out tests. Pretty cool, huh? (Pun sort-of intended)

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