Hyper-V Agent backups of a Windows 2012 Hyper-V Cluster generates VSS errors and causes the Clustered Shared Volumes (CSV) to fail over and the virtual machines to go offline.

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  • Article ID:000018781


When performing Hyper-V Agent backups on a Windows 2012 Hyper-V cluster a VSS snapshot error can occur followed by a failover of the Clustered Shared Volume (CSV) to another node. The virtual machines running on the CSV volume may go into a paused or offline state.


Error Message

- Snapshot Technology: Initialization failure on: "VRTSRV::\\CSVNAME\Hyper-V?HA?VM\VMname". Snapshot technology used: Microsoft Volume Shadow Copy Service (VSS).

V-79-10000-11226 - VSS Snapshot error. The Microsoft Volume Shadow Copy Service (VSS) snapshot technology selected returned: "Unexpected provider error". Ensure that all provider services are enabled and can be started. Check the Windows Event Viewer for details.
The following volumes are dependent on resource: "C:\CLUSTERSTORAGE\VOLUME1



Several known issues found and corrected by Microsoft when Virtual Machine backups are run in a Windows 2012 Hyper-V Cluster environment.



Apply the following Microsoft Hotfix to the Hyper-v Hosts:


Update that improves cluster resiliency in Windows Server 2012 is available




Applies To

Backup Exec 2012 SP2

Windows Server 2012

Hyper-V Cluster and Cluster Shared Volumes (CSV)



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