SGI also offers a 20-foot Ice Cube Air big enough for 10 racks, and a large module that's two 20-foot modules sandwiched together. Like the 8-foot module, the medium and large Ice Cube Airs can also be snapped together in fours. They are all on sale now, worldwide, Mannel said.

The containers can hold any vendor's gear and SGI will pre-install racks or customers can roll them in on site. The racks can all handle a maximum IT load of 25kW, which is as much as most customers should need.

Containerized data centers have taken off gradually since Sun Microsystems launched the first high-profile product, called BlackBox, about three years ago. They're now sold by several vendors including IBM, Dell and Hewlett-Packard, which recently opened a dedicated facility to build them.

They allow customers to add extra compute capacity quickly, if a data center expansion project is behind schedule, for example. They're also used in remote locations, by the military and other customers.

Like SGI, more and more vendors are moving away from standard shipping containers. I/o Data Centers, one of the newer entrants to the market, said a few months ago it would sell custom-built portable data centers.