Defrag task does not work on a deduplicated VHD file in Windows 8.1 or Windows Server 2012 R2

Applies to: Windows 8.1 EnterpriseWindows RT 8.1Windows 8.1 More

Symptoms


Consider the following scenario:
  • You run a virtual machine (VM) by using a VHD file that is not deduplicated.
  • You run a dedup job to deduplicate the VHD file.
  • You run a task in the VM that performs many write tasks on the VHD file and causes many recalls on the deduplicated file.
  • You run the defrag task.
In this scenario, the defrag task does not defragment the VHD file.

Resolution


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

Status


Microsoft has confirmed that this is a problem in the Microsoft products that are listed in the "Applies to" section.

More Information


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
This issue occurs because the Cluster Shared Volumes File System (CSVFS) volume does not unpin a file after the dedup job sets a reparse point on the file