Tuesday, November 10, 2009

Efficient UPS Aids Google’s Extreme PUE

Google continues to improve its energy efficiency, and is telling the industry how it’s doing it. After years of secrecy surrounding its data center operations, Google is disclosing many of its innovations today at the first Google Data Center Efficiency Summit in Mountain View, Calif.

In a morning presentation, Google engineers addressed its Power Usage Effectiveness (PUE) ratings, which have generated discussion within the industry since Google’s disclosed in October that its six company-built data centers had an average PUE of 1.21. That benchmark improved to 1.16 in the fourth quarter, and hit 1.15 percent in the first quarter of 2009, according to Google’s Chris Malone. The most efficient individual data center (described as “Data Center E”) has a PUE of 1.12.

“These are standard air-cooled servers, and best practices is what enabled these results,” said Malone. “What’s encouraging is that we’ve achieved this through the application of practices that are available to most data centers. There’s great potential for all data centers to improve their PUE.”

But there’s also some serious Google magic at work. One of the keys to Google’s extraordinary efficiency is its use of a custom server with a power supply that integrates a battery, allowing it to function as an uninterruptible power supply (UPS). The design shifts the UPS and battery backup functions from the data center into the server cabinet (see our February 2008 story describing this technology). This design provides Google with UPS efficiency of 99.9 percent, compared to a top end of 92 to 95 percent for the most efficient facilities using a central UPS.

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