Evaluate This – Hyper-V Server 2012
Hyper-V Server is a free operating system specifically designed to just run Hyper-V so basically a cut down core installation of a paid for edition of Windows Server. The cut down bit refers to the fact that only the roles and features needed to run Hyper-V are there. However Hyper-V itself is in no way cut down; for example you can create clusters for running HA virtual machines (up to 64 nodes hosting 8,000 VMs) and each VM can still have up to 64 logical processes as per the DataCenter edition of Windows Server.
So what’s the catch?
If there is one then it’s that if you want to run Windows Server in a VM it needs to be licensed and the most efficient way to do that once you get to 6-7 VMs per host is to use Windows Server DataCenter edition as this allows any number of guest VMs’ to be licensed for Windows Server as well as the hosts. However if you were going to use Hyper-V to host VDI then your guests need to be licensed for Windows 7/8 and so Hyper-V Server is a good candidate. Another example is if you want to just host Linux VMs which will run really well and are supported (depending on the flavour you are using).
I have made my usual short screencast to show you what it looks like..