{TAIL ~ Diagnosis} of {HEAD ~ the spare magnetic disk unit} 191 is conducted when a fixed time has elapsed 
{ TAIL ~ Diagnosis } of { HEAD ~ the spare magnetic disk unit } 191 is conducted when a fixed time has elapsed
TAIL TAIL TAIL TAIL TAIL OTH HEAD HEAD HEAD HEAD HEAD HEAD HEAD HEAD HEAD OTH OTH OTH OTH OTH OTH OTH OTH OTH