Virtualization has become the equivalent of "pixie dust, something you sprinkle on the data center, and suddenly everything runs better," said Mendel Rosenblum, co-founder and chief scientist of VMware, speaking tongue-in-cheek as he began a keynote address Thursday at the closing day of VMworld in San Francisco.

But by the time he was finished, some attendees may have forgotten he was joking. "A huge part of VMware's engineering is devoted to, how do I move these virtual machines around and manage them," he told the third-day attendees. "We've only scratched the surface of the value that can be added through the virtualization layer," he said.

Rosenblum demonstrated how virtualization allows a cheap form of mirrored systems that can guard against hardware failure. ESX Server virtual machines can now generate a log or record of their activity, and that log can be replayed in another virtual machine to show what happened.

A possible use of the capability is implementing it to guarantee the high availability of systems.

Rosenblum started a server on stage that was running the equivalent of 50 users pounding on Microsoft Outlook. The server's ongoing activity was being mirrored on a second server, which was receiving a live stream of events as they were entered into the log of the virtual machine on the first server.

As Rosenblum unplugged the first server, VMware's management software, Virtual Infrastructure 3, detected a failure and shifted handling the users to the secondary server. Since the secondary server was already receiving a stream of log events, it could pick up at the precise point where the other had left off. The pause between one virtual machine stopping and the secondary server's virtual machine starting appeared to be about a second.

"This approach works not for a few select applications, but for anything that runs in a VMware virtual machine," Rosenblum said. The demonstration was greeted with a wave of applause. In another example, Rosenblum demonstrated how end-user applications can be virtualized without strictly adhering to running them remotely in a software-as-a-service mode, like Salesforce, or adopting the alternative of a full download to the client. Virtualized end-user applications take several minutes to download.

Rosenblum said virtualization enables a "hybrid" approach that combines some elements of both. If a client machine is sent a small "stream manager," then that manager can examine a target application, detect priority settings already established on its files, and "prefetch" the files needed to start its operation before a full download is completed.

By adopting an approach in between streaming and software-as-a-service, the application starts to run after about 10% of the download occurs, making virtualized applications more palatable to end users, Rosenblum noted. No timeframe was set, but Rosenblum indicated such an approach will be made a feature of VMware's Virtual Desktop Infrastructure.

"What we're effectively doing is taking things that were statically assigned in the past and turning them over to virtual machine management software," he said. Virtual machines will enable a much higher degree of automation in the data center and make hardware a drop-in commodity that gets added as needed.