So this week I've been engaged by a client to consolidate their virtual infrastructure on to Hyper-V 2012 R2 from a mix and match of VMware and Hyper-V 2008 R2. The client had an unused Hyper-V 2008 R2 box that they had planned on migrating all of this stuff to and the box was not in production but was domain joined so I figured this was a good opportunity to try a in place upgrade of that server. So how about I jump right in.
Optional Prerequisite: While not necessary, I would recommend only doing this on servers you either have physical access, or have RMM/IP KVM access to. That way you'll be able to see what's going on during the reboots.
Step 1) prepare the server for the upgrade. Since this machine was not a domain controller I did not have to do any of the AD prep normally associated with an in place upgrade, so the only preparation step I did was make certain that windows updates were current.
Step 2) Next I installed pfmap173 which you can get here. This is a free Windows application that allows users to mount the contents of ZIP, ISO, Compact ISO, Compact File Set and Private Folder files to the file system as virtual folders. Very useful piece of software.
Step 3) Now that we have the ISO mounted, just run setup.exe and start the install.
Step 4) Selecting whether to get updates or not. It's going to recommend you get updates during the upgrade process, while I've done this with desktop upgrades from Windows 7 to Windows 8.1 and not had any issues, I really felt that since this was a server and I didn't want to drive an hour to go physically lay hands on it if something goes wrong, I chose to be as minimalist as possible and selected the option to not install the updates. This was purely intuition on my part, I can't cite a specific technical reason not to do this so your mileage may vary.
Step 5) Next step you will select what edition you are installing. Obviously this is going to be determined by the license key you have and in this case I'm going to do Standard, but I'll go over some basic facts about editions.
Data Center can be licensed for 2 sockets and gives you unlimited VOSEs with Automated Virtual Machine Activation. This basically means you can do an unlimited number of VMs on the Data Center host and the AVMA means they don't need to be activated through KMS or online. BUT, these VOSEs are not transferable to another host, so any cluster replication members must be Data Center as well or at least licensed for the total number of VMs that could be run if one host fails. Example: Host 1 has 2 VMs, Host 2 has 2 VMs and Host 1 and Host 2 are in a cluster, so that means Host 1 must be licensed for 4 VMs and Host 2 must be licensed for 4 VMs because if either host fails the subsequent host will be handling those VMs and must be licensed for them even if it's just for 1 second.
Core editions are pretty straight forward, it's basically whatever edition you have but without a GUI. This reduces servicing, management, resource consumption, and attack surface, all useful things in some scenarios. Your license keys can be used on both versions (with GUI and without).
Step 6) Select the upgrade option.
The install process will then examine compatibility, there are any issues you'll be notified here and it also spits out a report onto the desktop if you wish to cancel the process and go look at it. It will also warn you to go check with your software vendors to make sure software is compatible. I'm guessing you've already done this because you're not incompetent but just in case it gives you the option of stopping now and taking care of that.
Once you hit next, there's no going back, it's going to go through the unpacking and installing process and the machine will reboot several times.
If you don't have direct RMM/IPKVM access to the machine, you'll lose your RDP session and won't be able to connect again until the process is totally complete. When you're all done, you should be greeted by the lovely Server 2012R2 logon.
your friendly neighborhood IT solutions engineer