OS Licenses and VM Mobility

Migrating VMs from one server to another can still violate licensing rules for Windows Server. While many server applications, such as Exchange Server 2007, can be moved relatively easily when they are running in VMs, the rules governing the server OS that is running in the VM are more complex.

In the illustration above, purchased OS licenses are denoted with a dollar sign ($) while other server OS licenses are entitlements derived from the purchased licenses. Server 1 is a two-processor server which has two Windows Server 2008 Datacenter processor licenses. They entitle the customer to run any number of instances of any edition of the Windows Server OS in any VM hosted on that physical server. Server 1 currently hosts two VMs, one running Windows Server Datacenter, the other Windows Server Standard. Server 2 has a Windows Server Enterprise server license and hosts three VMs running Windows Server Standard, while Server 3 uses VMware’s ESX hypervisor. It has no Windows licenses and hosts VMs running Linux.