PROBLEM


In a Hyper-V cluster environment, backups of VM(s) on specific Hyper-V Host(s) are failing with error:

A problem with Windows Shadow Copy was detected. 

VSS Error Code: 779



CAUSE


VSS was unable to complete because either the CSV was currently in redirected mode, or the Hyper-V host could not take ownership of the CSV during the backup.



SOLUTION

  1. Ensure that there is no other application trying to backup any VM on the same CSV

  2. Ensure that the CSV has not been left in redirected mode

  3. a) For a Host Cluster Windows Server 2008 R2:

    Ensure that the Hyper-V Host that is hosting the VM(s) in question has authority to be an owner of the CSV. You can list the possible owners of a CSV by using the following command in command prompt on the Master Hyper-V Host:

    cluster.exe res "<cluster disk name>" /listowners
    Example:   cluster.exe res "ClusterDisk2" /listowners


    If the Host where the VM(s) are hosted is not listed, you will need to add them to the list of possible owners by using this command in command prompt on the Master Hyper-V Host:

    cluster.exe res "<cluster disk name>" /addowner:<new owner>
    Example:  cluster.exe res "ClusterDisk2" /addowner:node3


    b) For a Host Cluster Windows Server 2012 or 2012 R2:

    Ensure that the Hyper-V Host that is hosting the VM in question has authority to be an owner of the CSV. You can list the possible owners of a CSV by using the following command in Windows PowerShell on the Master Hyper-V Host:

    Get-ClusterSharedVolume | Get-ClusterOwnerNode


    You should get something like so:

    ClusterObject OwnerNodes 
    ————- ———- 
    Unidade_G {ServerA} 
    Unidade_H {ServerA, ServerB}


    If the Host where the VM are hosted is not listed, you will need to add them to the list of possible owners by using this command in Windows PowerShell on the Master Hyper-V Host:

    Set-ClusterOwnerNode -Owners ServerA,ServerB -Resource “Unidade_G”