'Update the initiator data at key with value.
If the key has already been set to something return False, otherwise
if saved successfully return True.'

def insert_driver_initiator_data(self, initiator, key, value, ctxt=None):

    try:
        return self._db.driver_initiator_data_insert_by_key(self._get_context(ctxt), initiator, self._data_namespace, key, value)
    except exception.CinderException:
        LOG.exception('Failed    to    insert    initiator    data    for    initiator    %(initiator)s    and    backend    %(backend)s    for    key    %(key)s.', {'initiator': initiator, 'backend': self._data_namespace, 'key': key})
        raise
