I realise this tool has been available in various flavors for quite a while now, but I still get a number of questions aroung licensing Windows Server for Virtualization & thought it would be worth writing a post about it for anyone out there reading my blog.

Lets start by looking at the Microsoft Windows Server Licensing Policy for Virtualization which states in brief:

Windows Edition	Physical Licenses	Virtual Servers Licensed
Standard Edition	1	1
Enterprise Edition	1	4
Datacentre Edition (Per Processor)	1	Unlimited

Ok so based on the above it is clear that selecting the correct version of Windows to assign to the physical server on which you are going to run server virtualization will have direct impact on your Virtualization ROI calculations.

No, its not rocket science to work this out for yourself, but then why do all that work when you dont have to? Microsoft have created and released a very nice little tool that does all this for you, along with rough estimate costs of each licensing model called the Windows Server Virtualization Calculator.

Simply find the correct tier based on the number of processors you are going to have, enter the number of physical servers in the server virtualization platform and finally the number of guest operating systems you will be running on average. The tool will do the rest for you.

Happy Virtualization.