I now have a nice new Hyper-V Server 2012 R2, replacing my previous Hyper-V Server 2008 R2. My "actual" servers are virtual servers that run in Hyper-V, of course (there are two at present: a domain controller and print server, plus a separate everything-Internet server running mail, several websites using various technologies, an SFTP server, and a torrent server*).
I had initially installed the Hyper-V Server as a testbed before setting up a much larger system at work (with clustered hosts and a big RAID-6 disk array). It has served me well. But some time after I upgraded my desktop to Windows 8.1, I discovered that the version of Hyper-V Manager that runs in Windows 8(.1) doesn't talk to Hyper-V 2008, only 2012. Bad move, MS, and a big step back from your generally excellent record in backward compatibility. First move, dig out an old machine and install Windows 7 so I could control (and in due course export and shut down) my servers!
Obvious second move: upgrade Hyper-V 2008 R2 to Hyper-V 2012 R2. What's this? The upgrade isn't possible! Second bad move MS! I have to do a clean install of Hyper-V 2012. Oh well, let's have a new machine as well - so one new motherboard and processor later (second motherboard - the first was not the one stated on the box!), I have a new machine ready to run my virtual servers.
OK - export; copy across; import. Now what? Ah. Third strike. Hyper-V 2012 R2 cannot import servers exported from Hyper-V 2008 R2. I can only do it by importing into Hyper-V 2012, and re-exporting from there. You think I'm setting up a third server?? Easy answer, actually - just create new virtual machines using the old virtual disks - as far as I can see the only setting that had to be redone inside the virtual machines was the IP address, as the new network interface is seen as a different device.
Actually, the whole transfer (once the new machine was waiting) took only about two hours (and another two for the torrent data, but the servers were up and running by then), with the 1Gbps network between the machine running at 95% of theoretical capacity, which impressed me. The performance of the servers is markedly better on the new host than it was on the old one, so that's good - and I'll use the old one (now running 2012 R2 as well) to run a hot backup of the servers, continuously updated, which is a new facility in this version - almost as good as a cheap cluster and RAID combination.
Oh, and I don't think I'll be trying this at work until we replace our current round of hardware!
*
Why have I got a torrent server, you ask? I seed for this site.