How to Build It

Stay flexible and keep an eye on your company's future needs

Today's data centers pack more processing power into smaller physical spaces than ever before. But too much of a good thing creates new challenges for next-generation data center design.

Consolidation has decreased the physical footprint but has created new power and cooling challenges. Ten years ago, data centers used 30 to 50 watts of power per square foot. Today's data centers gobble 150 to 225 watts per square foot, according to research firm DatacenterDynamics in San Francisco. "That number is going up steadily," says Joshua Aaron, president of Business Technology Partners Inc., a New York-based consultancy. "Blade servers and virtualization allow you to pack all this into a data center, and it requires more power for that equipment."

What's more, because data centers hog power and cooling resources, there's a big push to design them in a more energy-conscious way -- with recycled materials, raised floors for maximum cooling efficiency, and alternative natural power sources.

Add to the mix a need for complete redundancy in uninterruptible power supplies, and data center designers face a delicate, ongoing balancing act.

"I think the ultimate goal is to develop and operate a data center where you maximize the utilization of power within a given space for the lowest life-cycle cost without sacrificing reliability," says Jeff Monroe, executive vice president of strategy and business development at DuPont Fabros Technology Inc., a data center provider in Washington.

When building your next data center, your best bet is to be flexible and keep an eye on your company's future needs. Here are some goals to keep in mind.

Plan for Maximum Efficiency

Equipment must be configured in a way that is efficient to operate and maintain, Monroe says. "Space plans must allow for the efficient deployment of servers such that the end user can consume as much of the available power as possible while still optimizing heat transfer and rejection," he says.

Raised floors and efficient cooling and heat flow are helping with power efficiency.

Managed hosting provider Rackspace Hosting builds its new data centers with raised floors so cool air under the floor can be pulled up through the room and hot air can exit from the ceiling. Overhead air conditioning ducts require larger fans and water pumps and, consequently, use more energy. "In one of our data centers, we forecast as much as a 10% to 15% efficiency improvement by moving to an under-floor model," says Troy Toman, vice president of operations at San Antonio-based Rackspace.

Pod designs will also help data centers adapt to new technologies and customers' changing needs. Rackspace has eight data centers worldwide, with a 65,000-square-foot facility opening in London this year. "We try to take a just-in-time provisioning mode," Toman explains. Only a 20,000-square-foot portion of the London data center -- or one pod -- will open initially, he says. "In a year or two, when we need that next portion, we can re-evaluate the design decisions, and if there's a better way to design or do cooling, we'll do that," he says.

"Keep flexibility in the system so you don't lock yourself in," Toman adds. "You're talking about a data center that you're hoping is going to be around for 20 to 30 years."

Rackspace plans to use barriers, panels and curtain-like dividers to keep hot air that's vented from servers away from cool air. But Toman also wants to regulate the temperature through the use of sensors that will, for instance, make sure that server areas are kept cooler than cabling areas.

Design for Efficient Power and Cooling

Your next data center should feature power-saving technologies. DC power is one option to consider

DC is an efficient alternative to traditional AC power, but several issues have kept it from being widely adopted. Among other things, DC power is potentially more dangerous than AC power because the voltage remains high instead of alternating according to need, Aaron says. It's also expensive to implement. "Not all [equipment] manufacturers offer DC power options, and it's expensive to buy a DC power rectifier," he adds. "But the cost over time will start to come down."

Explore 'Greener' Options

Data center designers are also weighing the benefits of flywheels vs. batteries as sources of backup power. "Flywheel is much greener -- you're not disposing of batteries, and it has a clear ROI for not having to do battery replacement," Toman says. One drawback is that today's flywheels provide less than a minute of power.

"If everything works as designed, that's enough time for you to power the equipment to bring on the generator," he says. "But experiences show that eventually something won't work as predicted. If you've got 30 seconds, it had better work perfectly. If it doesn't, you just lost the whole backup computer." Toman suggests re-evaluating flywheels as the technology improves.

Seek out Renewable Power Sources

Experts suggest looking at renewable power sources, like the sun, wind and timber, when you're building your next data center. Rackspace's U.K. data center is being supplied by a utility that burns wood chips to produce energy. San Antonio, the site of another new Rackspace data center, is one of the leading locales for wind-based power generation in the U.S.

Tomorrow's data centers will also have "2N" backup designs, in which each uninterruptible power supply has its own backup UPS module.

Perform a Balancing Act

Too much of a good thing can diminish efficiency returns, experts caution. Continually weigh the benefits of smaller footprints vs. cheap real estate, and power costs vs. alternative energy sources.

"I really do not see this as a destination but more of a journey," Monroe says. "As technologies change, we continually look for opportunities to refine [the data center]."

Collett is a Computerworld contributing writer. Contact her at

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Next: How to pay for it: Minimize equipment and maximize space. 



Copyright © 2008 IDG Communications, Inc.

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