The vast, labyrinthine computer room of Veritas DGC Inc., in Houston, used to be a crowded, bustling place. Small groups of technicians would often hunker down there for hours in wired warrens formed by refrigerator-size racks housing more than 10 000 server—"nodes," in networking jargon. The technicians, known as "nodelers," worked day and night in that sprawling hive to keep all those machines up and running, processing the advanced geophysical and seismic models that are at the heart of Veritas's business.

These days, the oil industry consulting firm's computer room is much quieter and less crammed. The nodelers are still nodeling, but they spend considerably less time in the chilly computer room. Here's why: the number of servers that are down at any given time has dropped from 2 percent to 1 percent. It seems like a tiny improvement, but when you have 10 000 servers, that single percentage point means a hundred more units dutifully crunching data rather than idly waiting for a nodeler.

Image: Bryan Christie

Similar transformations are happening in computer rooms all over the world, and they are all the result of the same decision: to switch from conventional servers to blade servers. Blades, for most information technology departments, offer huge improvements over conventional, rack-mounted units. This compact, slim computer (hence the name "blade") is typically based on the same Intel or AMD processors and Windows or Linux operating systems as most other servers, but it consumes a lot less power and takes up a lot less room.

Blades fit into enclosures that hold several units, usually vertically and side by side, like books on a shelf. To replace a bad blade, a technician need only pop it out of its enclosure and put in a new one. And blades are equipped with management programs that let staff easily set them up for specific applications or arrange them in special configurations.

The greatest benefit of blades, therefore, is their flexibility. They are much easier to install, manage, and repair than conventional servers—especially when you have hundreds or thousands of units. That was the case, for example, for Weta Digital Ltd., a special-effects company in Wellington, New Zealand, founded by filmmaker Peter Jackson. It used more than 500 IBM blade servers, each with two Intel processors, to bring to life the digital characters and scenes of the final installment of The Lord of the Rings trilogy, The Return of the King (2003), which won an Academy Award for best visual effects.

The Barcelona Supercomputer Center in Spain also turned to blades when it decided to build a massive computer cluster late last year. The center mounted 2282 IBM blade servers in 27 racks, which took up less than 50 square meters [see photo, A Mass of Blades]. A similar system built with regular servers would likely require more than double that area.

The machine, dubbed MareNostrum, took fourth place last November in the biannual Top500 ranking of supercomputers compiled by the University of Mannheim, in Germany, and the University of Tennessee. MareNostrum is now the most powerful computer in Europe, according to that list.