Monday, June 29, 2009

The Cost of the Cloud

Data Center Overload
Tom Vanderbilt, NY Times Magazine, June 8, 2009

Data centers worldwide now consume more energy annually than Sweden. And the amount of energy required is growing, says Jonathan Koomey, a scientist at Lawrence Berkeley National Laboratory. From 2000 to 2005, the aggregate electricity use by data centers doubled. The cloud, he calculates, consumes 1 to 2 percent of the world’s electricity.

Much of this is due simply to growth in the number of servers and the Internet itself. A Google search is not without environmental consequence — 0.2 grams of CO2 per search, the company claims — but based on EPA assumptions, an average car trip to the library consumes some 4,500 times the energy of a Google search while a page of newsprint uses some 350 times more energy.

Data centers, however, are loaded with inefficiencies, including loss of power as it is distributed through the system. It has historically taken nearly as much wattage to cool the servers as it does to run them. Because of the complexity of the network architecture — in which the role of any one server might not be clear or may have simply been forgotten — turning off a server may create more problems (e.g., service outages) than simply leaving it on.

As servers become more powerful, more kilowatts are needed to run and cool them; square footage in data centers is eaten up not by servers but by power. As data centers grow to unprecedented scales — Google recently reported that one of its data centers holds more than 45,000 servers (only a handful of companies have that many total servers) — attention has shifted to making servers less energy intensive. One approach is to improve the flow of air in the data center, through computational fluid-dynamics modeling. "Each of these servers could take input air at about 80 degrees," John Sontag, director of the technology transfer office at Hewlett-Packard, told me as we walked through the company’s research lab in Palo Alto. "The reason why you run it at 57 is you’re not actually sure you can deliver cold air" everywhere it is needed. Chandrakant Patel, director of the Sustainable IT Ecosystem Lab at HP, argues there has been "gross overprovisioning" of cooling in data centers. "Why should all the air-conditioners run full time in the data center?"” he asks. "They should be turned down based on the need."

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