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