However, {HEAD ~ a time} for making a magnetic disk unit “operating” upon receiving an access is required, and the performance of {TAIL ~ the disk array unit} as a whole is significantly degraded 
However , { HEAD ~ a time } for making a magnetic disk unit “ operating ” upon receiving an access is required , and the performance of { TAIL ~ the disk array unit } as a whole is significantly degraded
OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH TAIL TAIL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH