The method 5, {TAIL ~ the first and second processors} further programmed for operating {HEAD ~ the second cluster} in a single cluster mode during the failback to service mode for the first cluster 
The method 5 , { TAIL ~ the first and second processors } further programmed for operating { HEAD ~ the second cluster } in a single cluster mode during the failback to service mode for the first cluster
OTH OTH OTH OTH TAIL TAIL TAIL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD HEAD OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH