z/VM

z/VM is the current version in IBM's VM family of virtual machine operating systems. z/VM was first released in October 2000 and remains in active use and development as of 2009. It is directly based on technology and concepts dating back to the 1960s, with IBM's CP/CMS on the IBM System/360-67 (see article History of CP/CMS for historical details). z/VM 5.4 runs on IBM's System z, System z9 and System z10 computers. It can be used to support large numbers (thousands) of Linux virtual machines.