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