Consider a disk queue holding requests to the following cylinders in the listed order: 210, 67, 11, 99, 87, 90, 19, 150. Using the C-SCAN scheduling algorithm, what is the order that the requests are serviced, assuming the disk head is at cylinder 88 and moving upward through the cylinders?
A) 87 - 90 - 99 - 67 - 19 - 11 - 150 - 210
B) 210 - 67 - 11 - 99 - 87 - 90 - 19 - 150
C) 90 - 99 - 150 - 210 - 11 - 19 - 67 - 87
D) 90 - 99 - 150 - 210 - 87 - 67 - 19 - 11

Question

Quizplus · Accepted Answer

C-SCAN (Circular SCAN) scheduling algorithm services requests in one direction until the end of the disk is reached, then jumps to the other end of the disk and continues servicing requests in the same direction. Starting from cylinder 88 and moving upward, the next requests serviced are 90, 99, 150, and 210. After reaching the end, it jumps to the beginning (assuming a wrap-around), servicing 11, 19, 67, and finally 87.

Consider a Disk Queue Holding Requests to the Following Cylinders