The controller unit carries out I/O accesses to and from the disk devices via the intermediary devices based on {HEAD ~ access requests} sent from {TAIL ~ host apparatus} 
sent from
The controller unit carries out I / O accesses to and from the disk devices via the intermediary devices based on { HEAD ~ access requests } sent from { TAIL ~ host apparatus }
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 REL TAIL TAIL TAIL TAIL TAIL TAIL