Hyper-V: Free or Licensed the Choice is Yours

Since October of 2008 there has been a version of Microsoft‘s Hyper-V that has been free to download. This version, to the surprise of some, includes a full version of Windows core, which means that you can bring up a fully functional Hyper-V host server without paying any licensing fees to Microsoft. For example, if you intend to run Linux Guests on your free Hyper-V server, you have the privilege of doing so without paying any money to Microsoft at all. On the other hand, if you intend to run Windows Guests the picture gets considerably more muddled, there are important economic and licensing trade-offs to be made.

What is in Each Edition?

Now what is interesting about is the fact that the free version supports all the newly introduced “Higher Functions” included in the Enterprise and Datacenter versions;  well except for the GUI, Application Failover, the ability to add extra Server roles like DNS or DHCP and “virtualization rights” but more about this later.

The chart below outlines the features of all the Hyper-V features:

At first glance it looks like you get more for free with Hyper-V than with VMware Free ESXi or XenServer, but I digress as that is not the focus of this article. So what is the best version to use in your production environment?

How Free is Free?

Are there any limitations on usage with the Server Core version of Hyper-V over the full fat versions?

Firstly, there are no virtualization rights with the free version, therefore every Windows guest will require a full license either retail or via an EA agreement.  That however, is not an issue if you are looking at virtualizing Linux Guests or a Windows based VDI solution: in the case of Linux the OS is free (support is costed), and in the case of a Desktop Virtualization environment, Microsoft Desktop Operating Systems are not included in the “Virtualization Rights” of the costed Hyper-V versions.

A limitation is that the free server core version can only be a Hyper-V host it cannot host any other services such as ADS, DNS or DHCP:  however that said, it is no real show stopper as your virtualization host should not be wasting processor cycles or real time memory usage on anything other than its core function running Guests. A more major limitation of the free version is that it is limited to 32GB of system RAM, and as Hyper-V does not have TPS or Memory over commit, this could be a serious limiter in guest density.

The Economic and Licensing Fees Comparison

When does it become effective to buy the DataCenter version of Windows 2008 rather than use the free version? To do this, we will need to set a line in the snow (well it is winter and the UK is currently white).  It is easier to do these costings using Retail pricing, as these costs are easily available: it is recognised that enterprises and larger SMB can get keener pricing and these numbers are only here as an example.

So for an average dual processor quad core machine utilising a free Hyper-V license there is no virtualization cost, whereas the same server licensed with Datacenter will have a upfront licensing cost of $5998.  However, and here is the crux of the matter, with the free version every Windows Server Guest you deploy on this host will need to be licensed. If you are deploying Standard Server, this costs $999 per instance,  so it is not too difficult to notice that a lightly loaded host with say 8 windows servers on it will be “cheaper”  under Datacenter licensing than Server Core.  It is also the case that if  you buy DataCenter  each Windows server license will be worth “more” as you deploy those Windows Servers as guests in the sense that each physical Windows Server license will buy you unlimited virtualization rights for Windows Servers running as Hyper-V Guests (a little note, these rights are the same for all Hypervisors).

However if you are looking at deploying a VDI infrastructure the situation is completely different. Microsoft “virtualization rights” do not include Desktop Operating systems, therefore the added license costs apply equally to both virtualization methods. If you use Datacentre or Enterpise you will be paying for a license you do not need – neither gives you desktop OS licenses.  The same is also the case if the deployed guests are to be Linux based.

So to sum up, which is better to deploy for production environments?  The answer is the usual consultants one of “it depends”.  For a traditional server based virtualization project, it makes financial sense to deploy Datacenter, and this is most likely the case for a hybrid deployment of Server and Desktop devices.  However, for raw VDI and Open source deployments, it is obviously more fiscally prudent to utilise the free version.