Operating Systems

Suppose that a disk drive has 500 cylinders, numbered 0 to 499. The drive is currently serving a request at cylinder 140, and the previous request was at cylinder 125. The queue of pending requests, in FIFO order, is 10, 470, 90, 170, 90, 150, 100, 250, 160 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 each of the following disk-scheduling algorithms?

a. FCFS =

b. SSTF =

c. SCAN =

d. C-LOOK =

e. C-SCAN =