'Get the lun ID for an exported volume.
If the lun is successfully assigned (exported) to a client, the
client info has the lun_id.
:param volume_name:  name of volume to query for lun ID
:param client_name:  name of client associated with the volume
:returns: integer value of lun ID'

def _get_lun_id(self, volume_name, client_name):

    v = self.common.vmem_mg
    lun_id = None
    client_info = v.client.get_client_info(client_name)
    for x in client_info['FibreChannelDevices']:
        if (volume_name == x['name']):
            lun_id = x['lun']
            break
    if lun_id:
        lun_id = int(lun_id)
    return lun_id
