- Posted by sondreb on March 25, 2008
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Today I decided to upgrade our Windows Server 2008 with the release candidate 0 of Hyper-V (the virtualization engine from Microsoft) and I stumbled upon various issues.
The first mistake I did was to download and run the patch without reading all the knowledge base and read me files... not a good idea!
Update for Windows Server 2008 (KB949219)
Update for Windows Server 2008 x64 Edition (KB949219)
On the bottom of the download page, there is a link to a knowledge base article that explains a little bit in details what's included with the RC0 patch.
http://support.microsoft.com/kb/949219
You have to read all the way to the bottom to discover that virtual machines created with the beta (which is included with Windows Server 2008 RTM) of Hyper-V is not compatible with the RC0. Buuu!
Trying to start an old virtual machine results in the error message illustrated above and the message: Failed to read or update VM configuration.
I would expect Microsoft to keep up with compatibility, or at least include an utility to upgrade virtual machines, but no. At least not for this release candidate - but I sure hope that Hyper-V RTM will have a much smoother upgrade story.
So then you hit another knowledge base article which describes what to do with your outdated virtual machines.
http://support.microsoft.com/kb/949222
Upgrading Issues
It tells you to delete all the snapshots on your existing virtual machines (make sure you take backup before doing anything) which should trigger an operation that merges the .avhd files in your Snapshots folder, with your .vhd files for all your virtual machines. To begin with I didn't see much activity, and I tried to boot one of my virtual machines (after re-creating it, if you try to start an old virtual machine configuration, you get the error message in the illustration above) and what appeared was a blank installation of Windows Server 2008! Whoops!
What had happened? Well, I had a moment of panic and tried to search for a solution to manually merge all my .avhd files with .vhd, but after a while I noticed that Hyper-V in fact was doing background processing and was actually merging my virtual hard drive files. It takes a very long time and I'm lucky I only have 10 virtual machines (I assume that the process length depends heavily upon the number of snapshots you have).
So when you begin the process of upgrading to RC0, make sure you have a good time for all your virtual machines to be down. Also make sure you do a full shut down of your virtual machines before you apply the patch. Preferably, I would have deleted all the snapshots before I installed the patch to avoid any unnecessary issues.
Networking Issues
Moving to RC0 changes the network settings on Hyper-V, which means it deletes your existing virtual network adapters when you're upgrading. This means you have to re-create it before you can move on.
If all of your virtual hard drives have merged (make sure you have NO .avhd files laying around any longer and that you're .vhd files has been modified) then you can start re-creating all your virtual machines. When you do this, you configure them with the same settings as before and connect them to your existing virtual hard drives.
When all your machines is back in shape, you'll need to start them up and reconfigure your network adapters. All of my virtual machines had static IP addresses and I had to reconfigure all of them AFTER installing the integration services (cause network adapter doesn't appear on the beta software when the host is RC0).
Integration Services Issues
This is the software that makes integration smoother between the virtual host and the virtual machines. Handles things like keyboard and mouse input. This software was upgraded with RC0 and to install it on Windows Server 2008 you have to run the patch that you originally ran for the virtual host.
With RC0, your mouse will no longer function if you're virtual machine is running beta version of integration services, so you'll get to freshen up on your Windows keyboard navigation skills :-)
On other versions of Windows, you just run the normal operation of Actions/Insert Integration Service Setup Disk, but how do you access the patch when your virtual machine no longer has network? I was unable to copy and paste from the virtual host to the virtual machine (maybe drag and drop works?).
So the solution I found was to search for a free .iso creation tool, download and install it and make a small .iso image with the Windows6.0-KB949219-x64.msu. Then load that .iso file into my virtual machine using the Insert Disk operation.
Overall Issues
I'm not writing a guide on how to do the upgrade process, you should try to follow the guidelines I've linked to above, but I was baffled when I read step number two in the process:
2. Document the configuration settings for each virtual machine.
Microsoft wants you to manually document the configuration of every single virtual machine - what if you had 20-40 or even hundreds of virtual machines in your network all running on Windows Server 2008 and Hyper-V beta? I was lucky with my 10 machines, but I used hours to go through this whole process of upgrading and I'm not happy with this at all.
Overall I'm happy with Windows Server 2008 and Hyper-V, the performance is very good and stability has been great. I would recommend it to anyone, but beware of the issues and make sure you read the documentation (which is still lacking due to the product not being finished, the included help file is missing a lot of sections).
Now get back to your virtual host server and upgrade Hyper-V!