Challenge

Guest VMs will fail to engage VSS when application-aware image processing is enabled generating an error:

 Error    Guest processing skipped (check guest OS VSS state and integration components version) (System.Exception)

Cause

This issue has multiple potential causes, usually related to the Integration Services version of the failing guest server. This issue occurs when Application-Aware image processing is utilized in the Backup or Replication job settings for transactional quiescence using Microsoft VSS

Solution

• A list of supported Guest OSes for each version of Hyper-V can be found here. 
• Important! Server 2012 R2 and higher guests are not supported for VSS-enabled (AAIP) backups on 2008 R2 hosts due to integration components incompatibility.
• If the VM Guest OS is 2012 and the Host is 2008R2:
  • View the Guest OS Application Event logs for errors with source: vmicvss and Event ID: 13.
  • If this error is present, open the Registry Editor (regedit) and navigate to:
    HKLM\SOFTWARE\Microsoft\WindowsNT\CurrentVersion\SystemRestore\
    Within that key create a new DWORD
    Name: ScopeSnapshots
    Value: 0
    Note: If the SystemRestore key is not present, you will have to create it.

The solution section of this knowledge base article has been split into 3 different sections. Please go over each step in each of the 3 sections.

1. Integration Services

How to identify…

Using Event Viewer

Using PowerShell (Server 2012 or newer)

1. Open Hyper-V Manager. From the Tools menu of Server Manager, click Hyper-V Manager.
2. Connect to the virtual machine. Right-click the virtual machine and click Connect.
   
3. From the Action menu of Virtual Machine Connection, click Insert Integration Services Setup Disk. This action loads the setup disk in the virtual DVD drive.
    
   Depending on the guest operating system, you may need to start the installation manually.
   
4. After the installation finishes, you may be prompted to restart.
   

2. Within the Guest

A.Make sure Windows is running the most recent service pack.

B.Ensure that the VSS Storage Area and Volume Match

1. From an Administrative Command Prompt, run the command ‘VSSUIRUN.exe”
   
2. Check the [Settings] for each Volume and ensure that the Volume and the Storage area match.
   

C.Ensure there are no Dynamic disk or FAT\FAT32 volumes

1. Open Disk Management (diskmgmt.msc)
2. Review the Type and File System columns
3. VSS is not compatible with Dynamic disks or FAT\FAT32
   
   All volumes must be NTFS or ReFS

D.Check System Reserved partition free space.

1. System Reserved partition must have more than 42MB of space free.
2. If less than 42MB is free, try creating a shadow copy for the volume.
   
   Remember to delete the Shadow Copy if it is successful.

E.Start\Restart the “Hyper-V Volume Shadow Copy Requestor”

1. Open Services (services.msc)

2. Find the “Hyper-V Volume Shadow Copy Requestor” service.

3. If it is ‘Stopped’, Start it.

4. If it is ‘Running’, restart it.

3. VM Configuration

1. Make sure the VM has a SCSI controller. One must be present, even if there are no devices to use the SCSI controller.
   
   The error will present itself in the Hyper-V VMMS > Admin Event log. Example:
   
   “The virtual machine ' Vm-Name' cannot be hot backed up since it has no SCSI controllers attached. Please add one or more SCSI controllers to the virtual machine before performing a backup. (Virtual   machine ID).”
2. Within the Virtual Machine settings verify that the “Backup (Volume Snapshot)” option is enabled. 
   
3. Make sure that the virtual machine files (VHD files) are not sitting in the root folder of the CSV, as this may prevent correct snapshot creation due to permission restrictions. We strongly recommend keeping virtual machine files in separate folder. More information regarding this can be found here.
   

1. Open an Administrator Command Prompt.
2. Run the command:
   Diskshadow /L C:\writers.txt
   
3. Run the command:
   list writers
   

More Information