The CSA primary device then migrates a portion of one of {HEAD ~ the logical data volumes} from one storage array to another to balance {TAIL ~ the data transfer loads} on the storage arrays 
The CSA primary device then migrates a portion of one of { HEAD ~ the logical data volumes } from one storage array to another to balance { TAIL ~ the data transfer loads } on the storage arrays
OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD HEAD HEAD OTH OTH OTH OTH OTH OTH OTH OTH TAIL TAIL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH