Disk Scheduling

Suppose that a disk drive has 5,000 cylinders, numbered from 0 to 4999. The drive is currently serving a request at cylinder 250, and the previous request was at cylinder 219. The queue of pending requests, in FIFO order is

87, 1250, 1024, 167, 1790, 1509, 832, 550, 45

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. LOOK

e. C-SCAN

f. C-LOOK