Assume that the Windows Server 2012 R2 Hyper-V hypervisor accesses the virtual hard disks (.vhdx files) on a Windows Server 2012 R2-based scale-out file server. The scale-out file server uses the Shared Virtual Hard Disk feature, and a cluster node is excluded from the scale-out file server. In this situation, a deadlock may occur when you stop a cluster service. This deadlock prevents the cluster shared volumes (CSV) from resuming access to the volume that hosts shared .vhdx files. Therefore, the volumes are stuck.
To resolve this issue, install update 2955164. For more information about how to obtain update 2955164, click the following article number to view the article in the Microsoft Knowledge Base:
2955164 Windows RT 8.1, Windows 8.1, and Windows Server 2012 R2 update rollup: May 2014
Microsoft has confirmed that this is a problem in the Microsoft products that are listed in the "Applies to" section.
For more information about software update terminology, click the following article number to view the article in the Microsoft Knowledge Base:
824684 Description of the standard terminology that is used to describe Microsoft software updates