It's not one of the first companies most IT managers associate with server virtualization, but Sun Microsystems' virtualization strategy is broad enough and adaptable enough to appeal to many customers who aren't already tied to VMware or Microsoft products, users and analysts say.\n\n"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. \nSun 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. \n\nSun'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. \n\nSolaris 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. \n\nIn 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. \n\nSun 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. \n\n"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." \n\nSun'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. \n\n"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." \n\nxVM 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. \n\nSun took Xen one step further by ramping up its capabilities for high-availability and performance. The company has added predictive self-healing, a technology that adds a software layer that can survive a CPU or memory failure and protect the applications that were running. It has also added its ZFS file system technology, which provides an advanced backup and snapshot technology for protecting guest virtual machines. \n\nWith Sun's virtual network technology, which will be available in the second half of this year, users will be able to hand out network shares, do bandwidth metering and limiting and "in effect let users guarantee the same quality of service in the same way as they do with the CPU," Wilson says. \n \nSun also is complementing xVM with a management platform called xVM Ops Center, which also will manage Sun Containers and LDoms at some point later this year. \n\nWhere does all this leave Sun competitively right now, compared to VMware and Microsoft? "IT organizations with favorable relationships with Sun have been interested in holding off on x86 virtualization projects until xVM Server matures," says Chris Wolf, a senior analyst with the Burton Group.\n\n"Sun has a lot of work to do to go after the x86 market and they face\nformidable competition," Wolf says. "Still, Sun has a very good end-to-end virtualization\nstrategy, and I think a number of organizations would look highly on a\ncentralized virtualization management stack that includes LDoms, Solaris\nContainers, and Xen-based virtualization." \n\nSun took the right approach in designing xVM to run VMware and Microsoft VMs\nunmodified on the Xen hypervisor, Wolf says. But he adds that convincing organizations with little or noSun installed base that Sun is the right virtualization vendor for them is\ngoing to take time. \n\n"At this point, I'm not ready to rule out Sun as a potential major competitor\nin the virtualization space," Wolf says. Deni Connor is principal analyst for Storage Strategies NOW, a research firm focusing on storage and server systems, in Austin, Texas. You can reach her at email@example.com.