Heading in a different direction from its main rivals, Ubuntu Linux will use as its primary virtualization software.
Red Hat Enterprise Linux and Novell's Suse Linux Enterprise Server both use the Xen virtualization software, a "hypervisor" layer that lets multiple operating systems run on the same computer. In contrast, the KVM software runs on top of a version of Linux, the "host" operating system that provides a foundation for other "guest" operating systems to run in a virtual mode.
"We've chosen to settle on KVM as our main virtualization focus," Soren Hansen, the Ubuntu Server Team's 26-year-old virtualization specialist, said in the Ubuntu Weekly News.
The move gives new prominence to KVM, which was initially popular with Linus Torvalds and other programmers of the Linux kernel. However, in the months since, the Xen programmers have made more progress in dovetailing their code more closely with the Linux kernel. KVM and Xen both are open-source packages.
KVM will be built into Ubuntu's next version, called Hardy Heron and due in April. "For the Hardy Heron release, we've really picked up the virtualization ball. Virtualization is making its way into data centers and onto developer workstations everywhere. Even 'regular' users are using it to run Ubuntu on Mac OS X all the time," Hansen said. "Virtualization has been on our agenda for a long time, but it became a top priority at UDS (Ubuntu Developer Summit) in November. We could see that demand for it was growing."
Canonical, the commercial sponsor of Ubuntu, will provide long-term support for Hardy Heron that lasts five years for servers and three years for PCs. Ubuntu is updated about every six months, but Hardy Heron is only the second version to get long-term support.
Xen is already built into Red Hat and Novell's Linux products, and Microsoft is on the brink of releasing its own virtualization product, called. However, the market leader for virtualization is EMC subsidiary VMware, which sells not only the virtualization foundation but also higher-level tools to monitor server performance and to move applications from one server to another to adjust work load.
Unsurprisingly, Xen fans see things differently. In particular, Simon Crosby, chief technology officer of, said KVM's approach is better suited to desktop machines than to servers.
"Ubuntu is not widely deployed in enterprise data centers, where the need for a comprehensive virtual infrastructure layer independent of any guest operating system...is a requirement articulated by every customer," Crosby said in a statement. Ubuntu is widely used on desktops, so for Ubuntu programmers, "it seems natural that a hosted virtualization model makes sense to them."
Although Ubuntu didn't use the same virtualization foundation that dominant Linux seller Red Hat chose, it will use the libvirt package Red Hat created to provide a neutral management interface to Xen, KVM, or other compatible virtualization systems.
To provide an easier interface to libvirt, Ubuntu will employ software called virt-manager, Hansen said. "It allows you to set up new virtual machine, see which ones are running, and how much CPU they're consuming," he said.