Performing a VM Upgrade from Windows Server 2008 to 2012

Rodney BarnhardtServer Administrator
Edited by: Sam Jacobs
With the end of support for Windows Server 2008, it has become necessary for organizations to migrate off of this operating system. However, this can be time consuming and problematic for IT departments. This is where being able to upgrade is an advantage.
For many years, the idea of performing an upgrade on a version of Windows server to a newer release has been avoided. Not only could they be problematic and unreliable, the idea of pulling all of that "old" configuration data through an upgrade was undesirable. In fact, as of the time of this writing, there are still organizations running on Windows NT 4.0 and Windows 98.

While this used to not be a great concern, with the expanse to cloud and more remote workers, the idea that all of these older operating systems are safe behind an environment secured by a firewalled perimeter is no longer true. Therefore, the need to be able to have security updates provided by Microsoft and install them is critical. It also seems that Microsoft has improved their update process, which appears to be more reliable and stable than past versions. However, as always, there are certain types of systems that should NEVER be upgraded - such as domain controllers, exchange and SQL servers. Always check if the services that are running support being upgraded.

The process described below has been tested and performed many times in a production environment. I developed this process in order to speed the move from the unsupported Windows Server 2008 to the supported Windows Server 2012 R2. It also provides a way to easily "roll back" to Windows Server 2008 in the event there is an issue.


1. The upgrade will create a folder for rollback purposes. Based on testing, this folder will be approximately 35-40GB. Verify that the appropriate free space exists. If not, then in Disk Management, add additional space before creating a VM snapshot.

2. In vCenter, create a snapshot of the VM. Give it an appropriate name, such as “Prior to 2012 Upgrade”.

3. In vCenter, edit the hardware settings of the VM by mounting the Windows Server 2012 ISO in the CD drive. Ensure the CD/DVD drive has the “connected” box checked.

4. Once mounted, log in to the CONSOLE of the VM, do not use RDP. Go to the CD/DVD drive and launch the setup program. Once at the prompt, select “Install Now”.
5. Since these systems are updated regularly, select “No thanks” on the updates screen.
6. For the operating system version, ensure you select “Windows Server 2012 R2 Standard (Server with a GUI). 
7. Accept the license terms.
8. Select the “Upgrade” option on the Windows Setup screen

9. The system will then run a compatibility report that will inform you if it is advisable. You can choose to ignore the report. It may say that an upgrade is NOT recommended.
10. If you continue with the upgrade, the process will then begin. It will take about 20-30 minutes to complete. During this time, the system may reboot several times. It is best to not monitor it until the process is complete.
11. Once the upgrade is complete, log into the system on the console.
12. In order for the VM to function properly, VMware Tools will probably need to be upgraded if they are not current.
13. If needed, vCenter will display a message similar to this one.

14. Click on the “Upgrade VMware Tools” on the right side, then from the console,  upgrade the tools and reboot the system.
15. Log back in, verify connectivity by successfully pinging another IP on the network such as the gateway.
16. Begin testing applications to ensure the system is functioning normally. DO NOT install Windows Updates yet!
17. If all tests are successful, the rollback folder will be deleted. Since there is a snapshot of the VM, this will be the rollback point. Therefore, the folder is not needed and the space can be reclaimed. To do this, in Server Manager go to “Add Roles and Features” and click Next until the Features option is listed. Expand “User Interfaces and Infrastructure”. Check the box next to “Desktop Experience”. This will add the disk cleanup feature to the OS. Continue clicking Next until the end, then Finish. Allow time for the feature to be installed. The system will then require a reboot.

18. Once installed, the properties of the C: drive will now contain the option to run “Disk Cleanup". Select this options to start the process.

19. The system will begin its calculations. In the listing of items that can be removed to free up space, you will see a checkbox labeled “Previous Windows Installations”. Select this checkbox and then continue.

20. Once the process is complete, perform Windows Updates. This will take several hours. With this being a different operating system, there will be well over 100 updates for the system to install.
21. After the updates have completed, place the system in production for a week or so to ensure it is functioning properly.
22. Once the system has been online as a Windows Server 2012 R2 for a sufficient period of time to determine that it is stable and functioning as expected, delete the snapshot. 

23. The upgrade is now complete.


While performing a Windows upgrade from an older operating system to a newer one is not always ideal, there are situations where this can be done successfully. Each system should be independently analyzed to determine if upgrading the system is better than rebuilding on a newer operating system. At least with the upgrade, the system will now be eligible to continue receiving monthly security updates from Microsoft. In today's landscape, being able to receive and install security updates is crucial for securing a network.

Rodney BarnhardtServer Administrator

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