Unmounting or removing a datastore in a HA cluster fails with the error: The vSphere HA agent on host failed to quiesce file activity on datastore

Products

• VMware vCenter Server

Issue/Introduction

Symptoms:

• Unmounting or removing a datastore in a high availability (HA) cluster fails.
• You are unable to unmount or remove a datastore in a HA enabled cluster.
• This issue occurs in a HA cluster used for datastore heartbeat or data persistence operations.
• In vSphere Client, you see the warning:
  
  The vSphere HA agent on host 'hostname' failed to quiesce file activity on datastore '/vmfs/volumes/volume id'. To proceed with the operation to unmount or remove a datastore, ensure that the datastore is accessible, the host is reachable and its vSphere HA agent is running.
  
  
• The vpxd.log file (located at C:\ProgramData\VMware\VMware VirtualCenter\Logs) contains entries similar to:
  
  T11:24:08.681Z [xxxxxxxxxxxx info 'vpxdvpxdVmomi' opID=OpId-xxxxxxxxxxxxx-1d] T11:47:34.730Z [FFF23B70 info 'vmomi.soapStub[2]' opID=OpId-xxxxxxxxxxxxx-1d-13] Resetting stub adapter for server <cs p:1f361840, TCP:localhost:443> : Closed
  T11:47:34.731Z [FFF23B70 verbose 'HalCnx' opID=OpId-xxxxxxxxxxxxx-1d-13] [HalCnx] Authenticate succeeded: userName=vpxuser
  T11:47:34.733Z [FFF23B70 info 'commonvpxLro' opID=OpId-xxxxxxxxxxxxx-1d-13] [VpxLRO] -- FINISH task-internal-1 -- -- csi.FdmService.login --
  T11:47:34.739Z [FFFA5B70 info 'commonvpxLro' opID=OpId-xxxxxxxxxxxxx-1d-8c] [VpxLRO] -- BEGIN task-internal-2 -- -- csi.FdmService.unsetDatastoreDisabled -- xxxxxxxx-xxxx-xxxx-xxxx-xxxxxxxxxxxx
  T11:47:34.740Z [FFFA5B70 verbose 'FDM' opID=OpId-xxxxxxxxxxxxx-1d-8c] [FdmService::UnsetDatastoreDisabled] invoked on datastore /vmfs/volumes/<volume ID>
  T11:47:34.740Z [FFFA5B70 info 'Invt' opID=OpId-xxxxxxxxxxxxx-1d-8c] [InventoryManagerImpl::UnsetDatastoreDisabled] Datastore (/vmfs/volumes/505dc9ea-2f199983-764a-001b7858bddc) not disabled. Do nothing
  T11:47:34.740Z [FFFA5B70 info 'commonvpxLro' opID=OpId-xxxxxxxxxxxxx-1d-8c] [VpxLRO] -- FINISH task-internal-2 -- -- csi.FdmService.unsetDatastoreDisabled --

Resolution

This issue is resolved in vCenter Server 5.1 Update 1a. 
To workaround this issue when you do not want to upgrade, disable vSphere HA from the Cluster settings, delete the affected datastore, and then re-enable vSphere HA.

For more information on disabling vSphere HA, see Disabling VMware High Availability (HA) (1008025).

Additional Information

Disabling VMware High Availability (HA)