"Sun has a virtualization product in every category that matters," says Al Hopper, an engineering consultant for Logical Approach in Plano, Texas and former member of Sun's OpenSolaris Governing Board.

Sun is offering server virtualization capabilities across all its hardware platforms; it offers virtualization technologies for x86-based, SPARC and UltraSPARC hardware, as well as for hardware from other vendors such as Dell and IBM.

Sun's main virtualization solution is based on Solaris Containers, a virtualization or partitioning technology built into the Solaris 10 operating environment that has been available on x86-based and SPARC server platforms since January, 2005.

Solaris Containers is an operating system virtualization platform that isolates or "contains" software applications within software-defined boundaries that maintain their own identity. According to Steve Wilson, VP of xVM for Sun, 25 percent of Solaris 10 customers use Sun Containers.

In December 2005, Sun further bolstered its virtualization strategy by introducing UltraSPARC T1 processor-based CoolThreads servers that came with built-in server partitioning or virtualization technology called Logical Domains (LDoms). LDoms lets as many as 128 physical servers be consolidated on one CoolThreads system.

Sun supplemented its Solaris Containers and LDoms virtualization technologies with the introduction of xVM, a platform for x86-based servers, in October, 2007. The company is presently beta testing vXM, which it released as open source and expects to ship this summer.

"Last year, we got much more aggressive on moving into the virtualization space with commodity x86-based hardware, as well the ability to work with Linux and Windows workloads in addition to just Solaris," Sun's Wilson says. "That's what has led us to the xVM strategy."

Sun's xVM strategy is not only for Sun-based hardware. Sun, according to Wilson, has close partnerships with Dell and IBM. In 2007, for instance, Dell inked a deal with Sun to distribute Solaris 10 on its PowerEdge servers.

"OpenSolaris runs on servers that aren't made by Sun," says Gordon Haff, senior analyst with research firm Illuminata. "There's no reason people wouldn't use the technology on non-Sun x86 servers."

xVM is based on the open source Xen virtual machine monitor (hypervisor) developed at the University of Cambridge in England. Xen has also been adopted for integration into Novell's SuSE Linux Enterprise Server, Red Hat's Enterprise Linux operating platforms, and Virtual Iron's Extended Enterprise Edition.