Hello OM12 SP1, Goodbye Windows Server 2008 R2 SP1!

With the upgrade of OM12 RTM UR#3 to SP1 Windows Server 2012 is now fully supported. So during the week-end I upgraded all my OM12 servers (and other System Center 2012 SP1 servers for that matter) based on Windows Server 2008 R2 SP1 to Windows Server 2012.

On itself a straightforward process. Again preparation is key here. Some lessons learned:

1. Make sure the logical disk running the Windows installation (normally the C:\ drive) has more then 15 GB of free space (13 GB of free space is the ABSOLUTE minimum);
   1. When the disk is too small, expand it. After a successful upgrade the disk can be downsized again.
2. When a Windows Server 2008 R2 SP1 DC has to be upgraded, prepare it first by inserting the installation media of Windows Server 2012 in to the DC and running these two commands:
   1. <Installation media>:\support\adprep\adprep /domainprep
   2. <Installation media>:\support\adprep\adprep /forestprep
3. When WSUS is installed, remove it;
4. When the server runs VMM 2012 RTM UR#3 Management Server, remove it (retain the database!);
5. OM12 SP1 Management Servers continue to function properly after the underlying Server OS upgraded to Windows Server 2012;
6. OM12 SP1 Gateway Servers continue to function properly after the underlying Server OS upgraded to Windows Server 2012;
7. SQL 2008 R2 SP1 x64 Servers – hosting the OM12 SP1 databases (among other SC 2012 SP1 databases) and SSRS instances – continue to function properly after the underlying Server OS upgraded to Windows Server 2012.

How to get rid of Windows.old folder after the upgrade to Windows Server 2012?
After the server is upgraded to Windows Server 2012 there is an useless folder in the root of C:\, titled Windows.old. This folder is BIG: ranges from 10 GB to 18 GB in size, depending on the role of the upgraded server.

So it’s better to remove that folder, but how? In Windows Server 2008 R2 you had the Disk Cleanup button located in the Properties screen of every logical disk shown in the Explorer. But in Windows Server 2012 this button isn’t present any more by default:

The folder Windows.old is locked by default so it takes some time to gain permissions on ALL those folders found in the main folder Windows.old. So that’s not the way to go.

Gladly in Windows Server 2012 there is a better way: Just get the earlier mentioned button back. How?

1. Start PowerShell on the related Windows Server 2012 machine;
2. Enter: Install-WindowsFeature Desktop-Experience and hit <ENTER>;
3. It will run for some minutes and report when ready;
4. Reboot the server, the feature will be installed and initialized while rebooting. This takes some minutes as well;
5. After the server is fully functional again the button Disk Cleanup is back again:
   
6. Hit the button and after the scan it will show you the option to remove the Windows.old folder, Previous Windows installation(s):
   
7. > OK > Delete Files
   
8. It will run for some minutes:
   
9. After a while the Windows.old folder is deleted. 
10. When required, the PS-cmdlet Remove-WindowsFeature Desktop-Experience will remove this feature again from your server.

Now you can shrink the volume through the Computer Management console. Afterwards you can compact the disk by using Hyper-V Manager.

Recap
Windows Server 2008 R2 SP1 is so 2012 . But seriously, servers running OM12 SP1 Management Server roles, OM12 SP1 Gateway Servers and SQL Server 2008 R2 SP1 instances can be upgraded to Windows Server 2012. Again preparation is key here. TechNet provides an excellent starting point for good information about this upgrade process.