July 2005

From the Lab: Information Technology

Cooling data centers, speeding up secure data transmissions, making Internet phone calls clearer, and more

By Monya Baker (editor)

The Heat Is Off
Data centers keep cool

Context: Server computers are housed by the thousands in buildings called data centers. All those servers humming together generate a vast amount of heat, which can make them malfunction. A 30,000-square-foot center can run up a bill of $8 million a year just for cooling, so data centers' floor plans are designed to make cooling more efficient. The servers are also governed by algorithms that optimally distribute work to reduce the total amount of power used. These methods, however, do not accommodate for temperature variations across a data center. Now researchers from Duke University and Hewlett-Packard Labs have shown that assigning tasks to servers based on such variations can slash cooling costs.

Methods and Results: When temperature in a data center isn't uniform, energy is wasted cooling the entire room just to keep machines in hot spots from overheating. Justin Moore and colleagues designed two algorithms that avoid creating local hot spots. One algorithm gives a server less work as its surroundings get hotter. The other surveys the entire data center and assigns fewer tasks to servers more prone to recirculate hot air.

Why It Matters: Moore and colleagues' work could drop the costs of doing business and keep servers from crashing. Computer models show that using the algorithms could reduce cooling costs by 25 percent, an annual savings of $1 million to $2 million for a large center. Data centers power today's Internet economy; with the new algorithms, they would be more reliable and use fewer resources.

Source: Moore, J., et al. 2005. Making scheduling "cool": temperature-aware workload placement in data centers. Paper presented at Usenix Annual Technical Conference. April 10-15. Anaheim, CA.