Diagram A below indicates that with Windows Server 2008 Enterprise, you may run one instance of the server software in the POSE and up to four instances of the server software in VOSEs. The orange arrow indicates that when running all five instances, the instance of the server software running in the POSE may only be used to manage and service the operating system environments on the server.
Note, when customers are running virtualized instances of the server software, they must be using some form of virtualization or “hypervisor” technology, such as Microsoft Virtual Server software, Microsoft’s new Hyper-V technology, or a third-party virtualization software.
Diagram B below indicates that with Windows Server 2008 Enterprise, you may move a virtual instance of the server software to another server that is properly licensed to support such added instance. Note that Server A is under-licensed because it is running one instance more than what is granted by the Enterprise license. For Volume License customers, the actual license may also be re-assigned to another server every 90 days.