<Li> The improved security, reliability, and device independence possible from hypervisor architectures </Li> <Li> The ability to run complex, OS - dependent applications in different hardware or OS environments </Li> <P> Major Unix vendors, including Sun Microsystems, HP, IBM, and SGI, have been selling virtualized hardware since before 2000 . These have generally been large, expensive systems (in the multimillion - dollar range at the high end), although virtualization has also been available on some low - and mid-range systems, such as IBM's pSeries servers, Sun / Oracle's T - series CoolThreads servers and HP Superdome series machines . </P> <P> Although Solaris has always been the only guest domain OS officially supported by Sun / Oracle on their Logical Domains hypervisor, as of late 2006, Linux (Ubuntu and Gentoo), and FreeBSD have been ported to run on top of the hypervisor (and can all run simultaneously on the same processor, as fully virtualized independent guest OSes). Wind River "Carrier Grade Linux" also runs on Sun's Hypervisor . Full virtualization on SPARC processors proved straightforward: since its inception in the mid-1980s Sun deliberately kept the SPARC architecture clean of artifacts that would have impeded virtualization . (Compare with virtualization on x86 processors below .) </P>

Which type of hypervisor is primarily used in test environments