Answer:
a. FCFS
seek: 9+4+6+16+16+28+32 = 111 cylinders, 555 ms
b. SSTF
seek: 5+16+4+30+2+2+2 = 61 cylinders, 305 ms
c. C-LOOK
seek: 5+16+4+30+2+2+2 = 61 cylinders, 305 ms
Explanation:
a. FCFS: requests are served in the order they are received. It is used when load is low and has long waiting time for long requests queues.
order: (15), 6, 10, 4, 20, 36, 8, 40
seek: 9+4+6+16+16+28+32 = 111 cylinders, 555 ms
b. SSTF: requests are served using shortest seek time first. It minimizes arm movement, and maximizes request rate
order: (15), 20, 36, 40, 10, 8, 6, 4 15 10 8 6 4 40 36 20
seek: 5+16+4+30+2+2+2 = 61 cylinders, 305 ms
c. C-LOOK: requests are served in one direction until when done then reverses. It does not go to end of disk.
Assume maximum track is 50 then reverses
order: (15), 20, 36, 40, (50), 10, 8, 6, 4
seek: 5+16+4+30+2+2+2 = 61 cylinders, 305 ms
