Consider a disk queue with requests for I/O to blocks on cylinders 98, 183, 41, 122, 14, 124, 65, 67. The FCFS scheduling algorithm is used. The head is initially at cylinder number 53. The cylinders are numbered from 0 to 199. The total head movement (in number of cylinders) incurred while servicing these requests is _______.
(a)500
(b)632
(c)690
(d)800
ANSWER:
Question 2
Consider the following disk request sequence for a disk with 100 tracks 45, 21, 67, 90, 4, 50, 89, 52, 61, 87, 25.
Head pointer starting at 50 and moving in left direction. Find the number of head movements in cylinders using FCFS scheduling.
(a)310
(b)324
(c)315
(d)403
ANSWER:
Question 3
Suppose a disk contains 200 tracks (0-199) and the request queue contains track no: 93, 176, 42, 148, 27, 14,180. The current position of the read/write head is 55. Now we have to calculate the total number of track movements of read/write head using FCFS scheduling.
(a)360
(b)661
(c)850
(d)900
ANSWER:
Question 4
Request sequence = {176, 79, 34, 60, 92, 11, 41, 114} and Initial head position = 50. What is seek time?
(a)510
(b)155
(c)120
(d)189
ANSWER:
Question 5
Suppose the order of requests are 70, 140, 50, 125, 30, 25, 160 and the initial position of the Read-Write head is 60. Find seek time.
