Quoting SearchServerVirtualization.com

VMware Inc. gets the lion's share of the attention around virtualization, but at least one user of SWsoft Virtuozzo, an operating system virtualization platform, says that going down the Virtuozzo path afforded his firm significant savings over VMware.

John Yanekian, director of network services at the National Association of Home Builders (NAHB), a trade association in Washington D.C., was using VMware GSX (now VMware Server) two years ago, but switched to Virtuozzo because of operating system license costs.

"It wasn't about performance, but TCO," Yanekian said. "What VMware was doing was loading in to an OS then running the VMs on top, and each OS had its own environment," he said. "Each and every [Windows] instance we installed needed its own license."

"VMware is great because you have a lot of flexibility to run NT and Windows 2003 – whatever – at the same time, but you pay for that flexibility," he said.

Virtuozzo, in contrast, only allows you to run a single operating system flavor. It works by creating an isolated partition – or virtual environment (VE) in Virtuozzo parlance -- off a single baseline OS. Because of that, SWsoft told Yanekian that NAHB would only have to buy a single Microsoft Windows Server license per host. On a machine with 10 guests, "instead of 11 Windows Server licenses with VMware, we only had to buy one," Yanekian said.

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