One of the great things about virtualisation, is that the host operating system running the hypervisor is independent of the operating system in the VMs. For example VMware ESXi is not the same as Linux and Windows operating system in the guest VMs that reside on it. You might be a little confused when you look at Hyper-V in the same way, but actually it’s the same again. You could run Windows Server 2012 Hyper-V and have Windows Server 2003/2008/200R2 in the VMs and contrary to popular belief Linux also works well on Hyper-V and is fully supported for the latest versions. Note: It is technically possible to run much older operating systems on Hyper-V, such as MS-DOS, OS/2, Windows for Workgroups it’s just that those aren’t supported because those operating systems aren’t supported at all even if they are ran on physical hardware.
The point I want make here is about what effect upgrading the hypervisor has on the guest operating system in the virtual machines. This can be likened to reinstalling that operating system on new hardware, which in turn means driver support. VMware Tools/ Hyper-V Integration Components provide these synthetic drivers to spoof such things as CPU storage, networking, time synchronisation and also feed back to the hypervisor the state and usage of these resources. So from the perspective of the guest operating system, moving hypervisors is the ripping and replacing of these drivers. Of course from the host this might mean a change of the metadata and hard disk files that represent that virtual machine on the host.
None of this is difficult but does involve some change albeit less than changing the guest operating system, but why bother upgrading or changing a hypervisor?
If I look at what Hyper-V offers in Windows Server 2012R2 compared with the original version that shipped with Windows Server 2008, then everything has got easier, faster, with corresponding improvements in high availability(HA) and the different but equally important world of disaster recovery (DR). Some of this is a reflection of what hardware can do now such as NUMA in CPUs, SR-IOV on network cards while other improvements have totally been down to reworking the hypervisor itself to provide access to parallel processing without getting caught up with waiting for availability of threads on cores in a CPU.
So you’d have to have some obscure use case to stop you upgrading from one to the other as there would be no license cost involved because Microsoft doesn’t charge for Hyper-V, just the licensing in the VMs - I am assuming you are already licensed for those! So in return for a bit of work you get access to all the new stuff in Hyper-V.
Of course you could also move from Hyper-V in whatever version of Windows Server to VMWare and use one of their many licensing options to suit your HA & DR needs and how many VMs per server you have and so on. In preparing your cost benefit analysis for this compared with moving to Windows Server 2012 R2, it’s worth bearing in mind that you’ll still need licenses for the operating systems in the VMs themselves whatever hypervisor you choose. Often the best way to do that is to license the host with Windows Server Datacenter edition which covers you to run as many VMs as you want on that host each of which is then licensed to run Windows Server and then covers you to run Hyper-V on the host as well. For a few edge cases that analysis might weigh in favour of VMware or be worth paying because of some particular feature like VM fault tolerance that doesn’t exist in Hyper-V. I say edge cases because I don’t see that happening a lot in the current market.
What I do see is movement from VMWare to Hyper-V. I don’t propose to do a feature comparison here (If you are interested then Keith Mayer’s post is as good as it gets) . What I want to focus on is three things:
1. Hyper-V advances over the last five years have outstripped enhancements in VMWare. For example the list of new features in Windows Server 2012 to 2012R2 all enhance Hyper-V in some way be that for VDI, for storage or DR. That rate of change isn’t evident in VSphere 5.1 – 5.5 most of which means the scalability numbers are in line with Windows Server 2012 R2.
2. Windows is Windows. If you know how to manage a windows server you can manage Hyper-V. This reduces the staff costs associated with running server virtualisation, because you don’t need a different team with different skills. A good example is to fire up Server Manager and see your physical hosts, alongside your virtual machines in one screen. This is actually good for us IT Professionals in those teams, we can either acquire a broad windows server knowledge including virtualisation in a smaller team or have the ability to transfer skills and have career progression in a larger one
3. Hyper-V is fit for purpose. While the Hyper-V that you buy in Windows Server 2012R2 is not exactly the same as the one runnning behind Azure , Office 365, Bing etc. there is a lot of common code. I could rattle out a list of references who are on Hyper-V now like Royal Mail, Unilever and Aston Martin, but perhaps the best evidence of Hyper-V being ready for business is silence. By this I mean that when things go wrong with anything technical these days forums and social media are alive with it very quickly and that has not been the case with Hyper-V.
So my assertion is that to upgrade your Hypervisor you need to consider Hyper-V