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