Part 1: To complete this assignment, consider the following scenario:

• A disk drive has 300 cylinders, numbered 0 to 299. The drive is currently serving a request at cylinder 51, and the previous request was at cylinder 56. The pending requests are received in the following order: 72, 56, 103, 111, 17, 189, 236, 198, and 88.

Describe how the disk arm moves to satisfy all the pending requests for each of the following disk-scheduling algorithms. (Perhaps you create a diagram similar to the diagrams in Section 9.4 to support your explanation.)

• FCFS
• SSTF
• SCAN

SAMPLE IMAGE

Calculate the total distance (in cylinders) that the disk arm moves for each of the above disk-scheduling algorithms. Compare the algorithms and explain which algorithm is the most efficient (the shortest distance) for this scenario. Write a minimum of 250 words.

Part 2:

Compare the algorithms and determine which is the fairest for the next process in the queue. Explain why this algorithm will always be the fairest disk-scheduling algorithm.

Describe an example of circumstances where fairness would be an important goal. Describe a scenario where it would be important that the operating system be unfair. Write a minimum of 250 words.

The Scheduling Models paper

• Must be a minimum of two double-spaced pages (500 words) in length

queue = 98, 183, 37, 122, 14, 124, 65, 67 head starts at 53 37 536567 98 122124 014 183199 Figure 9.4 FCFS disk scheduling. queue = 98, 183, 37, 122, 14, 124, 65, 67 head starts at 53 37 536567 98 122124 014 183199 Figure 9.4 FCFS disk scheduling