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Troubleshooting: Failed to Unmount and Detach Datastore with vSphere Plugin

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When customers try to Destroy a DataStore, they might get this alert:

“Failed to unmount and detach datastore. Please ensure that there are no registered VMs on this datastore and try again. 

Screen capture:


Applies to

vSphere plugin 4.2.x


Attempting to destroy a DataStore that meets certain conditions.


Before unmounting a LUN, ensure that:

  • If the LUN is being used as a VMFS datastore, all objects, (such as virtual machines, snapshots, and templates) stored on the VMFS datastore are unregistered or moved to another datastore.
  • Note: All CD/DVD images located on the VMFS datastore must also be unregistered from the virtual machines.
  • The datastore is not used for vSphere HA heartbeat.
  • The datastore is not part of a datastore cluster.

Additional Information

  • Please also ensure that this Datasore only uses Pure Luns.
  • If this datastore is used as a heartbeat datastore, you may need to switch that role. (Consult Vmware for this operation).
  • If there is any host in maintenance mode, make sure to rescan storage/hba for that hosts manually.

VMware Article

How to unmount a LUN or detach a datastore device from ESXi hosts (2004605)L: