Necessary to merge AVHD before in-place upgrade? 2008 R2 to 2012 R2 Hyper-V


  • Hi all-

    I am preparing to perform an in-place upgrade of Server 2008 R2 Standard to Server 2012 R2 Standard.  The only role installed is Hyper-V.  I am running 3 Server 2003-based VMs and 3 Server 2008 R2-based VMs.

    1.  I notice that several of the VMs have associated AVHD files.  I suspect they have been created by Backup Exec.  Is it necessary to merge these prior to upgrade?  I am aware that all VMs should be in the powered-down state.


    Monday, March 6, 2017 11:02 PM

All replies

  • I am preparing to perform an in-place upgrade of Server 2008 R2 Standard to Server 2012 R2 Standard.


    why do you want to upgrade a system with only the Hypervisor on it in-place? My recommendation, install it fresh with new drivers and without old issues and Export/Import your VMs.

    Before, proof your backups, start a validation Restore.

    Be careful, look at the growing and the date of the AVHD files. You Can also merge them manually via powershell if it´s not possible via GUI.


    I write here only in private interest

    Disclaimer: This posting is provided AS IS with no warranties or guarantees, and confers no rights.

    Tuesday, March 7, 2017 9:22 AM
  • I agree with Marcel that the recommended method to upgrade a Hyper-V host is to perform a clean installation.

    And, it is not really recommended to run VMs in production when they have snapshots, particularly in the 2008 R2 timeframe.  So it is recommended to clean that up before proceeding.

    Lastly, as a last recommendation, I would consider skipping 2012 R2 entirely and moving directly to 2016, particularly if you follow the recommendation to perform a new installation.  May as well move to the latest and greatest.

    . : | : . : | : . tim

    Tuesday, March 7, 2017 2:39 PM
  • Hi Sir,

    Also , please refer to following article regarding migrate from 2008r2 hyper-v to 2012R2 hyper-v :


    Best Regards,


    Please remember to mark the replies as answers if they help.
    If you have feedback for TechNet Subscriber Support, contact

    Monday, March 13, 2017 8:20 AM