A disk array unit connected to {HEAD ~ a host unit} to give information thereto and receive {TAIL ~ information} therefrom 
to receive
A disk array unit connected to { HEAD ~ a host unit } to give information thereto and receive { TAIL ~ information } therefrom
OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD HEAD REL OTH OTH OTH OTH REL TAIL TAIL TAIL TAIL TAIL OTH