Can you give a C programm about Shortest seek time first algorithm?

Answer 1

Suppose that a disk drive has 5000 cylinders, numbered 0 to

4999. The drive is currently serving a request at cylinder 143,

and the previous request was at cylinder 125. The queue of

pending requests, in FIFO order, is

86, 1470, 913, 1774, 948, 1509, 1022, 1750, 130

Starting from the current head position, what is the total

distance (in cylinders) that the disk arm moves to satisfy all the

pending requests, for each of the following disk- scheduling

algorithms?

A. FCFS

B. SSTF

C. SCAN

D. LOOK

E. C-SCAN

F. C-LOOK

Answer:

A. The FCFS schedule is 143, 86, 1470, 913, 1774, 948, 1509,

1022, 1750, 130. The total seek distance is 7081.

B. The SSTF schedule is 143, 130, 86, 913, 948, 1022, 1470,

1509, 1750, 1774. The total seek distance is 1745.

C. The SCAN schedule is 143, 913, 948, 1022, 1470, 1509, 1750,

1774, 4999, 130, 86. The total seek distance is 9769.

D. The LOOK schedule is 143, 913, 948, 1022, 1470, 1509, 1750,

1774, 130, 86. The total seek distance is 3319.

E. The C-SCAN schedule is 143, 913, 948, 1022, 1470, 1509,

1750, 1774, 4999, 0, 86, 130. The total seek distance is

9985.

F. The C-LOOK schedule is 143, 913, 948, 1022, 1470, 1509,

1750, 1774, 86, 130. The total seek distance is 3363.