If you’re in a non-subscription licensing program with Microsoft, then I recommend that you purchase Software Assurance with your Hyper-V licensing (this is the Enterprise or Datacenter licenses that covers your host OS and VM guest OS requirements).
There’s 3 reasons:
Every new release of Windows Server brings new features. We went from Windows Server 2008 with Quick Migration, to Windows Server 2008 R2 with Live Migration, CSV, and Dynamic Memory. That was nothing compared to what’s coming next year in Windows Server 8 (2012). And who knows what’ll come with Windows Server 8 (2012) R2!?!? You will want those upgrades … because we always have wanted them so far.
Guest OS Availability
Maybe you’re happy with Windows Server 2003/R2 for most of your P2Vd VMs for the next 900 or so days of remaining extended support. But at some point in the future:
- You will want to start deploying new VMs with the newest version of Windows Server that hasn’t been released yet
- You will want to upgrade/replace those legacy OS VMs
You could fall into the trap of thinking you can buy a few copies of Windows Server 8 Standard Edition for those few VMs on your Windows Server 2008 R2 cluster. Yes – but it wouldn’t be legal. That’s because you can only Live Migrate or Failover those VMs with the one-off licenses between different pieces of hardware once every 90 days. Those once-off licenses are assigned to hardware, not to VMs.
To be able to deploy a new version of Windows Server than you bought for the cluster, you need to upgrade the licensing for the entire cluster. You could go and re-spend all that money all over again. But you would save a lot of money by buying Software Assurance.
For those of you who sell software as a part of system integration/consulting services: you’d be a moron not to try to sell SA so you have a future upgrade project with your customer, and make available future opportunities to implement the newest features of the next version of Windows that could solve some problem the customer is having.
Windows Server 8 Hyper-V Replica, Veeam, Etc With Hosting Companies
If you replicate a VM from your licensed hosts to a hosting company of some sort using Hyper-V Replica (Windows Server 8) or one of the plethora of 3rd party alternatives, then you need to license the installation of Windows that is in each replica VM … even if it is powered off or locked in a replicating state. Don’t bother with any of the usual “it’s not being used” or “it’s only being replicated” arguments … it needs a license so that’s that.
A benefit of Software Assurance is Cold Back-ups for Disaster Recovery. This means that if you license your hosts (and thus your guest OSs if correctly licensed with Enterprise/Datacenter editions) with SA, then you get a benefit of licensing for the cold backup copy. The alternative is to not buy SA for the host/guests and have to buy full licenses for the offline replicas. This benefit allows your primary site to go offline and to power up the replicas during a catastrophic event. You can do this without doing anything to activate the benefit or without communicating with Microsoft.
Long time readers know I’ve been critical of SA in the past. There are times I recommend it, e.g. a customer wants Windows desktops and is considering looking at 3rd party encryption technology – Windows 7 Enterprise! I believe that it makes sense to purchase SA with Windows Server when licensing for Hyper-V because of the real benefits of host/guest upgrade and offline replica rights.