Virtualization Considerations

The use of hardware virtualization on servers addresses numerous challenges, including maximizing hardware utilization, lowering power consumption, accommodating temporary or intermittent workloads and peaks in demand, simplifying scheduled hardware maintenance, and assuring high availability through automated failover. Besides the virtualization limits associated with most Windows Server edition licenses, there are five other major points customers must understand when making Windows Server licensing decisions in environments where virtualization is or will be heavily exploited.

Only physical servers can be licensed. Server licenses for all editions of Windows Server are assigned to physical servers, not to VMs. Whether or not a customer has the right to run a Windows Server VM on a particular server is determined by what Windows Server license (or licenses) have been purchased and assigned to the physical server and the number of other Windows Server VMs already running at that moment. For example, a physical server with one Windows Server Enterprise Edition license assigned to it, and already running two Windows Server VMs, can run up to two more VMs without requiring additional server OS licenses.