When it comes to saving energy, Rackforce is doing better than most of us. Its three data centres in Kelowna, British Columbia, run computer applications for thousands of clients worldwide. Over the last four years, Rackforce has made those data centres 40 to 50% more energy efficient.
Rackforce did this in two ways, explains Tim Dufour, the company's president. First, in 2003, the company adopted a concept called server virtualization. This allows one physical computer to operate as several virtual machines. Although they share hardware, each virtual machine runs its own operating system and cannot see—or interfere with—the others. Most current servers are underutilized because they run only one application, to avoid the risk of programs interfering with one another. Dividing larger systems into virtual machines avoids wasting capacity while isolating each application, so no conflicts are possible. The energy savings are substantial, reducing power consumption by about 30%.
Then, last year, Rackforce took the next step, installing 320 new System x servers from IBM Corp. These machines use new quad-core processors that deliver more processing power per watt of electricity than older chips. "We have substantially increased the amount of computing power with less actual electricity consumption," Dufour says.
Braden Harrison, national brand and marketing manager for System x servers at IBM Canada in Markham, Ontario, points out that his company isn't the only computer maker offering more energy efficient hardware. Much of the improvements stem from the makers of the processor chips at the heart of the machines—Intel Corp. and its smaller rival, Advanced Micro Devices. It's all part of a new focus in the computer industry on what manufacturers call "performance per watt."
This is good news for the environment. But the motivation isn't the Kyoto Accord—it's money. For some data centres, Harrison says, power is a bigger cost than the hardware itself.
And the cost of the electricity is only half the story, because electricity generates heat. In densely packed data centres, it's essential to get rid of that heat or the equipment will crash. "For every watt of power used," Dufour says, "you have to use at least a watt of power for cooling." This becomes not just a money problem, but also a space issue. Data centres may have floor space available for more servers, but there's no room under the floor to run more power cables and no space to add more ventilation. Electric utilities may also lack the infrastructure to deliver more juice. "With fair regularity, we see people who just can't get any more power in," says Andrew Hillier, chief technical officer and co-founder of Cirba Inc., a firm in Richmond Hill, Ontario, whose software helps data centre managers plan virtualization projects.
Dividing computer servers into multiple virtual machines is popular not just because it saves power, but because it makes better use of the costly hardware. Typically, says Bogomil Balkansky, director of product marketing at VMWare Inc., a maker of virtualization software based in Palo Alto, California, a single processor can handle about four virtual servers. Many servers have two or four processors, so virtualizing eight or 16 servers on one physical machine is common.
Getting one computer to do the work of 10 doesn't mean using just 10% of the power, Hillier cautions. Processors consume power as long as they are running, but the busier they are the more they use, he says. Often a new virtualized machine will be more powerful—and hence use more energy—than the several servers it replaces.
But on average, Balkansky says, every application moved to a virtual server saves 3,000 kilowatt hours in annual server-power consumption, and as much again on cooling.
It isn't always necessary to divide a server into virtual machines to use it more efficiently, Hillier adds—sometimes it's enough to run several applications together without giving each one its own virtual server.
