"It's not just the computers themselves that use all this power: the combined heat output of all these servers, hard drives and network gear is so large that massive air conditioning is required to keep it all from overheating. "Cooling is about 60 percent of the power costs in a data center because of inefficiency," said Hewlett Packard executive Paul Perez in Data Center News. "The way data centers are cooled today is like cutting butter with a chain saw." Cooling capacity is often the limiting factor of how big these systems can be — I've talked with more than one engineer whose data center facility sat half empty or more; even though there was plenty of room for more servers, the building's air conditioning was maxed out.
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