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