Subject: Operating System

Topic: File Management And Input- Output Managemen

Difficulty: Medium

Suppose that a disk drive has 200 cylinder,numbered 0 to 199.The initial head position is at 100th track.The queue of pending requests in FIFO is 55,58,39,18,90,160,150,38, 184.Calculate average seek time for each of the following algorithm.

1.FCFS 2.SSTF 3.SCAN 4.C-SCAN.

First Come First Serve (FCFS) Disk Scheduling

Total Head Movements

= (100 - 55) + (58 - 55) + (58 - 39) + (39 - 18) + (90 - 18) + (160 - 90) + (160 - 150) + (150 - 38) + (184 - 38)

= 45 + 3 …