KV Pharmaceuticals, a specialty pharmaceutical firm in St. Louis, wanted to virtualize desktops and turned to "containers" rather than the virtual machine approach.

The difference might seem minor. In effect, Parallels, with its Virtuozzo product (formerly offered through SWsoft), partitions a hardware server into logical units that function under the host server's operating system. Virtual machines, on the other hand, each have their own operating system; you need as many copies of the operating system as the number of virtual machines that you plan to create.

Sun Microsystems used the container approach in Solaris 10 before it launched its xVM Xen-based hypervisor. IBM also uses the equivalent of containers on the mainframe with its logical partitions, or LPARS.

So what's the benefit of containers? With the container approach, memory consumption and processor overhead are reduced through the use of one operating system per host.

Ben Foxx, systems architect for KV Pharmaceuticals and its implementer of desktop virtualization, says his company "can get three to four times more virtualized desktops using Virtuozzo, running under Windows 2003 Server" than it could with a virtual machine approach.

For KV Pharmaceutical, a host is an HP ProLiant two-way server running dual-core processors. Under Virtuozzo, he can run 30 to 40 desktops per server, versus the nine to 10 VMware virtual machines he's been able to run on such a host. His breakeven point is nine users per host, so with Virtuozzo, he's saving money. That favorable ratio "is the reason why we came up with the whole idea," he said in an interview.

So far he has had 45 end users running in containers for seven months. By this time next year, he wants 200 virtualized desktops; he'll still have 400 to go. But some KV Pharmaceutical customers don't want the KV end users they work with tied to virtual machines. The area of concern is KV lab workers or researchers focused on KV's specialty drugs. A few customers don't want any technology they don't understand intervening between the lab workers and the results they're reporting, lest there be an unexplained glitch in the results, he noted.

Nevertheless, as KV switches to desktop virtualization, it is retiring older PCs and giving end users a Wyse S10 or V10 thin client tied to a Virtuozzo container. End users run standard Windows XP applications in the container along with specialized lab applications, and are connected by Microsoft Remote Desktop Terminal protocol services. Foxx estimates desktop virtualization software costs $80 per user and the thin client $200 per user. Each desktop PC or laptop that gets replaced has a price tag of $800 to $1,700, and thin clients may have twice the lifespan of PCs, he said.

But direct comparison between virtual and PC expenses is elusive. Some part of server expenses must be allocated to end users under the container approach, and then there's always the question of end-user maintenance. Foxx thinks the real savings lies in reduced end-user support. "Servers don't go out like PCs do. You don't have all these video card and motherboards going bad," he said.

End users see a personal desktop -- their Windows XP application settings are stored with their container profiles -- and it starts up faster than a PC. So far he claimed container performance was comparable to PC performance, and the security of user desktops has been solid, said Foxx. These factors have smoothed the way to end-user acceptance.

"We have never been able to go and just back up complete desktops," he added. "With Virtuozzo, I can."