Consider a disk queue with requests for I/O to blocks on cylinders 98, 183, 37, 122, 14, 124, 65, 67. The head is initially at cylinder number 53. We will now use the SSTF algorithm to serve these I/O requests.
Input: I/O requests - { 98, 183, 37, 122, 14, 124, 65, 67 }
Initial head position - 53
(a)500
(b)774
(c)236
(d)856
ANSWER:
Question 2
Consider a disk system with 100 cylinders. The requests to access the cylinders occur in following sequence-4, 34, 10, 7, 19, 73, 2, 15, 6, 20. Assuming that the head is currently at cylinder 50, what is the time taken to satisfy all requests if it takes 1 ms to move from one cylinder to adjacent one and shortest seek time first policy is used?
(a)119
(b)558
(c)315
(d)850
ANSWER:
Question 3
Consider a disk queue with requests for I/O to blocks on cylinders 19, 80, 134, 11, 110, 23, 162, 64. The head is initially at cylinder number 50. We will now use the SSTF algorithm to serve these I/O requests.
Input: I/O requests - { 19, 80, 134, 11, 110, 23, 162, 64 }
Initial head position - 50
(a)750
(b)263
(c)950
(d)4700
ANSWER:
Question 4
Consider a disc queue with requests for I/O to blocks on cylinders 95, 180, 34, 119, 11, 123, 62, 64. The head is initially at cylinder number 50. We will now use the SSTF algorithm to serve these I/O requests.
Input: I/O requests - { 95, 180, 34, 119, 11, 123, 62, 64 }
Initial head position - 50
(a)563
(b)263
(c)225
(d)236
ANSWER:
Question 5
Q.Consider the following disk request sequence for a disk with 90 tracks 12, 34, 52, 14,25,68,39. R/W head is starting at 53. Find the number of movements using SSTF scheduling.
