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