It’s been said that everything old is new again, and nothing could be more true than that with system virtualization. The introduction of virtual machine and hypervisor technology aboard x86 server hardware is arguably the most exciting development to emerge in years, but this technology, however new it is aboard the x86 server platform, is hardly new. Virtualization and system partitioning have existed for decades aboard mainframe systems from IBM running OS/390, z/VM, and z/OS and, more recently, aboard IBM’s iSeries and pSeries platforms as well as on HP’s HP 9000 and Integrity product lines. What’s new is the concept of bringing this virtualization technology to small and medium-scale x86-based servers.