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.