Blade servers are compact because blades?processor, memory and storage on a card?reside in rack-mountable enclosures that supply power, ventilation and other support components. Like most cluster-based systems, blade servers can be configured to include load-balancing and failover (another blade can automatically step in to take the place of a failed card). Individual blades are usually hot-pluggable, which makes it easy to swap out a board with a new one in the event of system failure (for more details, see "Servers on the Edge," www.cio.com/printlinks).

As enterprises begin to recognize blade servers’ potential to save space and cut costs, the technology has become increasingly popular. More than 150,000 individual blades were shipped in 2003, says Jeffrey J. Hewitt, a principal analyst at Gartner. That’s a big jump from the year before when just 30,000 units shipped, he says. And market researcher IDC (a sister company to CIO’s publisher) predicts that 2.2 million blades will ship worldwide by 2007, representing 27 percent of all new servers sold.

Mission for Mars

The Mars Space Flight Facility at Arizona State University (ASU) is using a BladeRack system from RackSaver. The Mars team installed the system in January 2003 and uses it to translate the thermal emission imaging system data, gathered by instruments on satellites orbiting Mars, into clean, detailed images that are suitable for study. The facility’s images helped NASA find optimal landing spots for the January 2004 landings of the Mars rovers.

Low cost, reliability and raw computational power are important to a program that performs cutting-edge science under a tight budget. "We usually build most of our computers in-house," says Gorelick. "We elected to buy the BladeRack because the vertical profile of each blade takes less space than an equivalent product we could build. Also, the community cooling, power and networking remove several per-machine failure points."

The biggest problem the Mars team experienced with its blade server was moving it into the building. "We were unable to get it into the Space Flight Facility without laying it on its side," says Gorelick. To reduce the unit’s weight, allowing it to be safely tipped over, all of the blades had to be removed. The handling took its toll on the blades, however. "To no one’s surprise, several ended up DOA, and several more died within the first month," says Gorelick. The blades were quickly replaced, though, and the system has since operated without any major problems.