Thus, {HEAD ~ a portion} of the data stored on each of the storage arrays 114, 116 and 118 is migrated to {TAIL ~ the storage array} 120 
is migrated to
Thus , { HEAD ~ a portion } of the data stored on each of the storage arrays 114 , 116 and 118 is migrated to { TAIL ~ the storage array } 120
OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH REL REL REL TAIL TAIL TAIL TAIL TAIL TAIL TAIL OTH