Well, I have finished upgrading all of my Hyper-V servers from the SP1 beta release to the SP1 release candidate – so I thought I would share some notes from my experience.

Unfortunately you cannot go directly from the beta release to the release candidate – instead you need to uninstall the beta (taking your system back to RTM) and then install the release candidate.  This requires some special planning when it comes to virtual machines with Dynamic Memory or RemoteFX enabled.

Hyper-V on the RTM release of Windows Server 2008 R2 does not understand how to read the configuration of a virtual machine which has either of these features enabled.  Once you have uninstalled the beta release of service pack 1 – opening the Hyper-V manager will not show any virtual machines which had these features enabled – and if you check the event log you will see entries like this:

Nothing untoward has happened to the virtual machine – and once you install the release candidate build the virtual machine will magically return.

That said – there are two specific things you should check for before beginning the process:

• Dynamic Memory / RemoteFX should be disabled on critical infrastructure virtual machines. 
  
  In my case I had to disable Dynamic Memory on my domain controller before attempting the update.  If I had not done this my domain controller would not have come up when I uninstalled the beta – and I would have been in quite a bind.
  
  
• Check to make sure that there are no virtual machines that have Dynamic Memory / RemoteFX disabled – but have snapshots where these features are enabled.
  
  It is okay to have snapshots present on virtual machines, it is even okay to have a mix of snapshots with these features enabled or disabled, but there is a problem that specifically happens if you have a virtual machine that has Dynamic Memory / RemoteFX disabled – but has snapshots where these features are enabled.  In this case the RTM version of Hyper-V will successfully load the virtual machine configuration – but will fail to load all the snapshots.  This can result in corruption of the missing snapshots.

After you have checked these two items the process is fairly straight forward:

• Uninstall SP1 beta
  
  
  • To do this you should first open the Control Panel
  • Then select Uninstall a Program (or Programs and Features if you have changed the default view of the Control Panel)
  • Then select View installed updates
  • After this select the entry labeled Service Pack for Microsoft Windows from under the Microsoft Windows section
  • Finally click Uninstall
  • After a period of time (and a reboot) your system will be back to the RTM release
    
    
• Install SP1 release candidate
  
  
  • This is pretty simple – so I will not detail the steps
    
    
• Update integration services on all your virtual machines

Cheers,
Ben