If the number n of {HEAD ~ the requests} being processed is less than 2 , control is passed to step 14, the LBA as a median point of the logical block address LBA of the disk devices 13 and 14 is calculated, and {TAIL ~ the obtained value} is set as a boundary LBA 
If the number n of { HEAD ~ the requests } being processed is less than 2 , control is passed to step 14 , the LBA as a median point of the logical block address LBA of the disk devices 13 and 14 is calculated , and { TAIL ~ the obtained value } is set as a boundary LBA
OTH OTH OTH 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 OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH TAIL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH