{HEAD ~ 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 clusters 
is coupled to
{ HEAD ~ 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 clusters
HEAD HEAD HEAD HEAD HEAD HEAD HEAD HEAD HEAD REL REL REL 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 OTH