Higher power loads need more infrastructure
November 20, 2012
Today's tip is to know the needs of denser data centers. As servers become more compact, they take up less space, but require much more energy. "Companies can now incorporate blade servers, which can hold up to 42 servers per rack," says Paul E. Schlattman, vice president, mission critical facilities group, Environmental Systems Design. The new servers may now need only two racks where old servers would have needed 10.
Servers may also need less physical space because of virtualization, says Schlattman. In the past, each server would use only 8 to 10 percent of its capacity, because it would run only a specific type of software. With virtualization, on the other hand, servers can run multiple platforms, "so now my server is running at 80 percent of its capacity," says Schlattman. "This also increases the need for power, because the (server) is running hotter."
As density increases, so does the need for support infrastructure: power transformers, uninterruptible power supply (UPS) systems, computer room air conditioners (CRACs) and chillers, and air distribution systems. In the highest tier data centers, support infrastructure may occupy four to six times the amount of space needed to house the computers. The higher the kilowatt load the computers are supporting, the more the infrastructure will be needed.
"Ten years ago, 500 kilowatts [of power] was considered to be robust; today 1,000 to 5,000 kilowatts of power is robust," says R. Stephen Spinazzola, vice president, RTKL Associates. A single computer cabinet may have been powered by one kilowatt 10 years ago, but it now uses 50 kilowatts. "It is hard to distribute that much power and cooling in a small space," Spinazzola says. The most common mistake in legacy data centers is to keep increasing computing power in the same amount of space, without thinking about how the facility can supply all that power and cooling to support the increased IT load, Spinazzola says.
Avoiding that problem requires the facility management and IT departments to be in close communication. The facility department needs to know about IT plans that could increase density, while IT has to be informed about how much capacity the infrastructure has.