After all the chat about Windows Server 2012 licensing and how to license WS2012 for virtualised environments, how many times have you seen a mention of CALs? Not very often, I’d say.
Windows Server does require you to count processors (2 at a time) but it is not per-processor licensing like with SQL Server. Unlike SQL Server per proc, you still need to buy CALs for any users/devices (depending on your CAL type choice) that authenticate against Windows Server.
Note: this post is about volume licensing, and not OEM and not SPLA.
For example, you have 1000 users. Your 50 servers are running Windows Server 2008 R2 and you have 1000 user CALs for Windows Server 2008 R2. If you decide to upgrade your 2 DCs to WS2012 then you need to 1000 WS2012 CALs.
The cheapest way to “upgrade” CALs is to purchase them with SA. Some will look at the cost and balk at it. But go ahead and buy them without SA. You’ll soon find an LOB app that requires WS2012 and you’ll have to “upgrade”. And then you’ll find that there is no upgrade. It’ll be a flat-out repurchase, and SA will look pretty good then, especially when you look at all the additional benefits in includes.
What about virtualisation? You only buy CALs for the services your users/devices are accessing. Your users don’t access Hyper-V. You can buy WS2012 for your hosts, and continue to run WS2008 R2 in your VMs. If no VM runs WS2012 as the guest OS, then your W2008 R2 CALs are OK. But upgrade a virtual Exchange, a virtual SharePoint, or a virtual file server to WS2012 and you’ll need WS2012 CALs.