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A confusion that has come up many a time regarding how to license Windows Servers when adding virtual machines on the Per Core licensing model as opposed to the old school deprecated method when you just had to license virtual machines and there was no thought about cores. Specifically when adding on top of the first 2 virtual machine servers, i.e 3+ Windows virtual machines.

We’ve looked into this a number of times and re-affirmed how to license virtual machines for Windows Server OSes. The core licensing model started with Windows Server 2013. And has applied to all Windows Server Standard and Datacenter licenses for 2013, 2016, 2019 and 2022.

This applies whether you are running the hypervisor VMware vSphere, Hyper-V, KVM, Xenserver, etc.

Windows Server 2013,2016,2019, 2022 Core Licensing

We reviewed current requirements and determined all cores of the physical server must be licensed, regardless of whether the VM is only using 4 cores or 32. If the server is 32 cores then that’s what is licensed since you “always license the Hardware” Microsoft licenses virtual machines based on the number of CPU cores in the physical hardware not by the VM.”

Licensing_brief_PLT_Licensing_Microsoft_server_products_for_use_in_virtual_environments (1).pdf

Basically every time you want to add more VMs to that physical host you have to increase the number of cores exponentially – since each fully licensed server allows 2 instances of the OS to be licensed.

Windows Server license terms permit customers to run up to two instances of Standard per Licensed Server (e.g., on the physical server and in one guest VM (referred to as “virtual operating system environments” or “virtual OSEs” in licensing), or in two guest VMs) and unlimited instances of Windows Server Datacenter per Licensed Server. Customers needing more than two VMs on a server licensed for Standard edition have the option of relicensing all of the physical cores on the server to permit two additional running instances.”

REF: Page 3 of this article – Windows_Server_2019_licensing_datasheet_EN_US.pdf

See also page 11 of this article for a diagram of the above licensing choreography:

Licensing_brief_PLT_Introduction_to_Microsoft_Core_licensing.pdf

Minimum window server 2013,2016,2019, 2022 License

The minimum you can purchase for one physical server is 16 cores. For 2 socket servers, that would be 8 cores each. That would license you to spin up 2X Windows Sever virtual machines with up to 16 cores each.

If you had a server with 10+ cores in each of the 2 sockets, you would need to purchase licenses for 20+ core licenses for the initial 2 VMs. If you need another 1 or 2 VMs after that, you would purchase the same 20+ core licenses – even if your new VMs only needed 4 or 8 cores and didn’t need the full assignment of cores available.

If you require further help, please leave a comment and we will answer it as soon as possible. 

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