RHEV : Snapshot fails with error MetaDataKeyNotFoundError for VM

Issue

• Unable to delete a snapshot image for a VM .
• Unable to migrate images across Storage domains.

Engine logs

2016-07-31 16:41:00,536 ERROR [org.ovirt.engine.core.vdsbroker.irsbroker.CopyImageVDSCommand] (org.ovirt.thread.pool-6-thread-40) [502b5aed] Failed in CopyImageVDS method
2016-07-31 16:41:00,536 ERROR [org.ovirt.engine.core.vdsbroker.irsbroker.IrsBrokerCommand] (org.ovirt.thread.pool-6-thread-40) [502b5aed] IrsBroker::Failed::CopyImageVDS due to: IRSErrorException: IRSGenericException: IRSErrorException: Failed to CopyImageVDS, error = Meta Data key not found error: ('{}:VOLTYPE',), code = 751
2016-07-31 16:41:03,774 ERROR [org.ovirt.engine.core.bll.ExportVmCommand] (org.ovirt.thread.pool-6-thread-40) [502b5aed] Command org.ovirt.engine.core.bll.ExportVmCommand throw Vdc Bll exception. With error message VdcBLLException: Failed during ExportVmCommand (Failed with error MetaDataKeyNotFoundError and code 751)

Vdsm logs

Thread-380546::ERROR::2016-07-31 20:17:02,948::task::866::Storage.TaskManager.Task::(_setError) Task=`b84bc7a7-ab0b-4773-a9ef-e667c1da19b3`::Unexpected error
Traceback (most recent call last):
  File "/usr/share/vdsm/storage/task.py", line 873, in _run
    return fn(*args, **kargs)
  File "/usr/share/vdsm/logUtils.py", line 45, in wrapper
    res = f(*args, **kwargs)
  File "/usr/share/vdsm/storage/hsm.py", line 1797, in copyImage
    pool.validateVolumeChain(sdUUID, srcImgUUID)
  File "/usr/share/vdsm/storage/securable.py", line 77, in wrapper
    return method(self, *args, **kwargs)
  File "/usr/share/vdsm/storage/sp.py", line 1907, in validateVolumeChain
    image.Image(self.poolPath).validateVolumeChain(sdUUID, imgUUID)
  File "/usr/share/vdsm/storage/image.py", line 636, in validateVolumeChain
    chain = self.getChain(sdUUID, imgUUID)
  File "/usr/share/vdsm/storage/image.py", line 195, in getChain
    if srcVol.isLeaf():
  File "/usr/share/vdsm/storage/volume.py", line 716, in isLeaf
    return self.getVolType() == type2name(LEAF_VOL)
  File "/usr/share/vdsm/storage/volume.py", line 658, in getVolType
    self.voltype = self.getMetaParam(VOLTYPE)
  File "/usr/share/vdsm/storage/volume.py", line 922, in getMetaParam
    raise se.MetaDataKeyNotFoundError(str(meta) + ":" + str(key))
MetaDataKeyNotFoundError: Meta Data key not found error: ('{}:VOLTYPE',)