Question

Suppose that a disk drive has 2,000 cylinders numbered 0 to 1999. The drive is currently serving a request at cylinder 142, and the previous request was at cylinder 125. The queue of pending requests in FIFO order is:

86, 1470, 913, 1774, 948, 1509, 1022, 1750, 130.

Starting from the current head position, what is the total distance (in cylinders) that the disk arm moves to satisfy all the pending requests for the following disk scheduling algorithm Scan

Answer 1

7080

Step-by-step explanation:

Let totaldistanceincylinders (total seek distance)=x=0

Its

142-86=56 x=56

1470-86=1384 x= 56+ 1384=1440

1470-913= 557 x= 1440+557= 1997

1774-913=861 x= 1997+ 861=2858

1774-948= 826 x=2858+826=3684

1509-948=561 x=3684+561=4245

1509-1022= 487 x=4245+487=4732

1750-1022=728 x=4732+728=5460

1750-130=1620 x=5460+1620=7080

hence, total distance in cylinders = 7080

This is the total seek distance.