Cassatt's new module takes advantage of the fact that Sun Microsystems' Java software already employs virtualization, said Rich Green, a former Sun Microsystems employee and now executive vice president of products. Each Java program already runs in a software environment called a Java virtual machine.

Cassatt's new module controls Java software by assigning new computing resources if performance isn't up to preset levels or moving it to a new machine if the one it's running on fails. It also lets administrators pool Java server resources into a central resource, replacing large numbers of underutilized servers with fewer machines running closer to top capacity. "We're seeing server consolidation numbers of about five to one," Green said.