This came up recently for a customer and while it’s not new news, I thought a quick reminder would be useful. There are a few key points to remember about licensing of Windows Server 2012 in server virtualization projects, these rules apply to XenServer, VMware, Hyper-V, Oracle VM, etc.:
- Licenses are applied to physical servers, never to virtual machines. If you are thinking about how you need a license for the VM you are about to build, you’re probably doing something wrong
- There is feature parity between Standard and Datacenter editions, Enterprise Ed has been dropped
- The only difference between these 2 major editions is in the number of virtual OSE’s (operating system environments, aka a virtual machine) granted with the license
- A license covers 2 processor sockets within 1 server, 1 license cannot be purchased to cover 2 servers each containing 1 populated processor
- The license allows for one bare-metal install of the operating system, but doesn’t require it – as would be the case if your hypervisor is anything other than Hyper-V
- Virtual OSE grants by edition:
- Standard: 2 virtual OSE’s per license
- Datacenter: unlimited OSE’s per license
- More than 1 license of the same edition may be applied to a given physical server to cover additional CPU sockets or additional virtual machines
- 2 Standard Edition licenses would cover 4 processor sockets and/or up to 4 VM’s
- 2 Datacenter Edition licenses would cover 4 processor sockets and two * unlimited for the number of VM’s ..that’s like beyond infinity, but 4 CPU sockets.
- The license cannot be transferred more than once every 90 days – yeah, you read that right. This rule is to prevent a license from jumping from one host to another to follow live migration activities
- This is where most people pause and say “oh..”. That tells me they were purchasing 1 license per VM and just thinking the license moves around with the VM
- You need to cover the high water mark of virtual OSE’s for a given host
- Licensing math:
- Standard Ed. list pricing is $882
- Datacenter Ed. list pricing is $4809
- The break-even point for Datacenter is at 5.45 Standard licenses; in effect, for a density of more than 10 VM’s (5 std licenses each granting 2 OSE’s), you should use a Datacenter Edition license
- A real world example: New virtualization customer deploying 3 VMware hosts
- We generally size the environment for N+1, meaning we’re planning that 1 of the servers is a “spare” from the perspective of workload sizing – so all the workload can run on just 2 servers; we’re planning for this and so should you in your licensing.
- If you plan to run more than 20 total VM’s in this environment, you need 3 Datacenter Edition licenses
- 20 VM’s running on 2 servers = 10 VM’s/server
- 10 VM’s requires 5 Standard Edition licenses to have enough OSE grants
- More than 10 per server, and it’s now cheaper to have just bought a single Datacenter Edition license
- 6 * $882 = $5292, which is greater than $4809 for datacenter
- Since you don’t know which host (think of a rolling patching cycle) is going to carry the increase load, all the hosts in the environment should be licensed uniformly to this high water mark
- Depending on the licensing model, an upgrade from 5 * Standard Edition licenses to a single Datacenter Edition license may not be possible – plan ahead!
- If you have OEM licenses that came with your old physical server environment, these are likely not transferrable – they don’t follow the P2V action
- With this understanding, while you might have some work to do upfront (or scrambling to get back into compliance now) the long term savings are very real for dense virtualization projects that can leverage the Datacenter Edition license. On a modern 2 socket server with 16 cores/32 threads, 10 VM or greater density is easily achievable
General licensing FAQ:
http://download.microsoft.com/download/4/D/B/4DB352D1-C610-466A-9AAF-EEF4F4CFFF27/WS2012_Licensing-Pricing_FAQ.pdf
Licensing brief for virtualized environments:
Lewan IT Solutions Technical Blog 