A data storage control unit is coupled to {TAIL ~ one or more host devices} and to one or more physical storage units, the storage control unit configured as a plurality of {HEAD ~ clusters} 
A data storage control unit is coupled to { TAIL ~ one or more host devices } and to one or more physical storage units , the storage control unit configured as a plurality of { HEAD ~ clusters }
OTH OTH OTH OTH OTH OTH OTH OTH TAIL TAIL TAIL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD