Data centers could cut their energy use by as much as 75 percent by putting idle servers to sleep when they’re not being used, say researchers at the University of Michigan.

The research team plans to present a paper on the subject next Tuesday at a conference in Washington, DC.

After analysing data center workloads and power consumption, assistant professor Thomas Wenisch and students David Meisner and Brian Gold used mathematical modeling to develop an energy-saving strategy they call PowerNap. Combined with a more efficient power supplying technique known as RAILS (for “Redundant Array for Inexpensive Load Sharing”), PowerNap could help dramatically reduce data center energy consumption.

This doesn’t mean servers would be dozing for hours at a time. According to the team’s research, the average idle period for a server can be measured in hundreds of milliseconds. That might be quicker than the blink of an eye, but it’s still far greater than the average busy period, which clocks in at tens of milliseconds.

Without frequent naps, however, all those multi-millisecond idle periods add up.

“For the typical industrial data center, the average utilization is 20 to 30 percent,” said Wenisch. “The computers are spending about four-fifths of their time doing nothing. And the way we build these computers today, they’re still using 60 percent of peak power even when they’re doing nothing.”

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