There’s always been some confusion around how Microsoft licenses Windows Server for use in a virtual environment. Believe it or not, Microsoft has an outstanding licensing program for Windows Servers, even if you’re not using Hyper-V as your hypervisor. Here’s how it works:
- If you buy a Windows Server Enterprise license (sold on a per instance basis), you are allowed to run up to 4 virtual machines with that license.
- If you buy a Windows Server Data Center license (sold on a per processor basis), you are allowed to run and unlimited number of Windows Server instances using that license. You don’t need to actually run the software, just buy a license for each physical server that will be hosting Windows Server instances. So, if you’re running six vSphere hosts and each has dual processors, you can buy twelve Windows Server Data Center licenses and cover every Windows Server virtual machine on the six hosts.
Note that desktop instances are not covered by these licenses. The license conditions are for server editions only.