The computing center already had a 4-megawatt substation serving its area of the site. "So it was a fairly simple matter to put a 220-kilowatt power pane on the outside of that and bring up a fairly standard chiller unit and put that on a concrete pad next to the Blackbox. Both of those things could just be fork-lifted in and connected up," Boeheim said.

SLAC wanted to do a rigorous installation that would last several years, so it spent a few weeks getting the unit hooked up. It had to reconnect about half the power cords which had shaken loose during the truck ride. Aside from that, the installation went smoothly and the machines were turned on for batch work Sept. 25, about two months after delivery. The 60-ton chiller and the outside power unit were also delivered in that time.

Servicing the unit has presented some challenges. "We're trying to figure out how to do it on a day like today when it's pouring with rain," Boeheim said recently. "The wind doesn't have to be blowing very hard for the rain to blow in the end, and you pretty much have to open both ends of the box to service it,"

It's quite cramped in the box, he said, and both ends need to be open so that a person can maneuver when a server rack is slid out into the narrow central aisle.

"Our stance right now is to wait for a clear day to open it up," he said. Two people are needed to service the box in case one gets trapped inside or injured, he wrote in the white paper on his Web site. SLAC put a phone in the box in case someone gets locked in.

The first Blackbox gave the center a roughly 25 percent boost in computing capacity, and the servers have been running as smoothly as their counterparts inside the datacenter, Boeheim said. "Once we got them turned on, they just ran. We went a full 30 days not even opening the thing." He put rack servers in the box rather than storage gear, because storage gear tends to need servicing more often, he said.

Sun's Blackbox won't be for everyone. Brookhaven National Laboratory, on Long Island, N.Y., considered a Blackbox but decided on a new wing for its datacenter instead, Boeheim said. SLAC's experience may have been easier than that of an average business because it is a federal government site located on county land. A business in a city may need more planning permissions and permits.

A few other companies offer comparable products, such as the Ice Cube from Rackable Systems, and the Infrastructure Express from American Power Conversion.

Sun said it is happy with the momentum for Blackbox, although it wouldn't say how many customers it has. The other three it named are Hansen Transmissions, a Belgian industrial manufacturer that is using one at a new plant in India; Mobile TeleSystems, Russia's largest mobile operator; and the Radboud University Nijmegen Medical Centre in the Netherlands.

Most of the customers had no room to add capacity in their datacenters, said Darlene Yaplee, vice president for integrated platforms in Sun's systems marketing group. "Half the customers are using it while they build extra datacenter capacity, and then it will remain for disaster recovery," she said.

The next size up in standard shipping containers is 40 feet long. "We could do 40 feet technically, but most people have been happy with 20 feet," Yaplee said. Boeheim said he'd probably choose a wider box rather than a longer one, which would accommodate his Dell 1950 servers.