Yesterday I attended an internal License training where the whole Microsoft licensing was explained. And although the licensing thing is not really my cup of tea there were some interesting cases that covered several real-world scenarios. Before we go any further I must say that I'm not a licensing expert and everything I'll write on my blog is my understanding of the licensing structure of Microsoft. If you are in doubt about your own questions please contact Microsoft directly and ask for one of their licensing gurus. Furthermore I must say al prices used in these cases are based on average prices and in real life are different, depending on your contract with Microsoft
Let's start with the most interesting case, the licensing of a virtual environment. As you'll probably know Windows 2008(R2) is available in several editions. Apart from the technical differences I'll explain the licensing differences:
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Windows Server Standard: around 395 Euro
This version is licensed per server. A physical deployment will give you the right to run one virtual instance.
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Windows Server Enterprise: around 1270 euro
This version is licensed per server. A physical deployment will give you the right to run up to four virtual instances.
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Windows Server Datacenter: around 1290 euro
This version is licensed per physical processor. A physical deployment will give you the right to run unlimited virtual instances.
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So if you are using a single host, with dual quadcore processors and we would like to run on that host a total of 4 virtual machines the cheapest way to do so is using Windows Server enterprise. (you would need 4*standard; 1*enterprise or 2* Datacenter). |
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Now we have 8 VM's running on the same host. This means you would need either 8*Standard, 2*enterprise or 2*Datacenter. |
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With nine VM's or more it is obvious that datacenter is the way to go. In that case you would need 9*Standard or 3*Enterprise or 2* Datacenter. |
This is really clear in my opinion, but how about clustering, live/quick migration, or if you're using VMWare, how about vMotion ?
In these conditions each host requires the correct license. Now that's interesting. For example, let's take a two node Hyper-V 2008R2 cluster with both nodes running a single quadcore Processor. Both nodes are hosting 4 VM's.
As we have seen in the previous example Windows standard is not really an option so I'll exclude it in this example. When running under normal conditions we would need either 2*Enterprise or 2*Datacenter, both are comparably priced. But what If one of the nodes (Let's say Node B) is down (for maintenance) and the VM's are failed over to the other Node (A)? All of sudden we would need 3 * Enterprise to comply while 2*Datacenter would still be enough. Even more interesting, what happens if the Node A needs maintenance and the VM's are running on Node B. Now we need to have 4*Enterprise vs 2* Datacenter.
This is the reason that when building a high available virtual environment you almost always need the datacenter license. Also keep in mind that the underlying virtualization technology has no influence on the licensing. So his example would still be the same If we would use VMWare or Xen.
Later this week I will write a blogpost about the licensing in a VDI scenario.