Unable to import storage domain in RHEV cluster

3 node RHEV- cluster running RHEV Hypervisor - 7.1 - 20150827.1.el7ev, RHEV-M running Red Hat Enterprise Virtualisation Manager Version: 3.5.5-0.1.el6ev and Data/NFS share was /export/vmdata

Both the RHEV cluster and RHEV-M manager lost power suddenly and powered down. On restart the storage domain was not able to be imported into the cluster.

The following was noted in the /var/log/ovirt-engine/engine.log

2015-11-16 22:21:35,899 WARN [org.ovirt.engine.core.bll.lock.InMemoryLockManager] (ajp-/127.0.0.1:8702-3) Trying to release exclusive lock which does not exist, lock key: 20b998a9-e1f3-4e80-8fa2-2012f6a2f12d STORAGE
2015-11-16 22:21:35,899 INFO [org.ovirt.engine.core.bll.storage.AttachStorageDomainToPoolCommand] (ajp-/127.0.0.1:8702-3) Lock freed to object EngineLock [exclusiveLocks= key: 20b998a9-e1f3-4e80-8fa2-2012f6a2f12d value: STORAGE
2015-11-16 22:21:35,888 WARN [org.ovirt.engine.core.bll.storage.AddStoragePoolWithStoragesCommand] (ajp-/127.0.0.1:8702-3) CanDoAction of action AddStoragePoolWithStorages failed for user admin@internal. Reasons:
VAR__TYPE__STORAGE__DOMAIN,VAR__ACTION__ATTACH_ACTION_TO,\
ERROR_CANNOT_ADD_STORAGE_DOMAIN_WITH_ATTACHED_DATA_DOMAIN

Noted the 20b998a9-e1f3-4e80-8fa2-2012f6a2f12d lock key from /var/log/ovirt-engine/engine.log
Removed the following two lines from /export/vmdata/20b998a9-e1f3-4e80-8fa2-2012f6a2f12d/dom_md/metadata

POOL_UUID=
_SHA_CKSUM=

Re-ran the import of the storage domain successfully.