Suppose that a disk drive has 40 cylinders, numbered 0 to 40. The drive is currently serving a request at cylinder 20 (the previous request served was at cylinder 19) when the last of these requests is made with none of these requests yet served. The queue of pending requests, in FIFO order, is 5, 25, 18, 3, 39, 8, and 35. A seek takes 5ms per cylinder movement. Starting from the current head position, what is the total distance (in cylinders) that the disk arm moves to satisfy all the pending request and alsocalculate the total seek time needed to serve these requests, for each of the following disk-scheduling algorithms? Explain with the help of a diagram in each case. a. FCFS b. SSTF c. SCAN d. LOOK
Suppose that a disk drive has 40 cylinders, numbered 0 to 40. The drive is currently serving a request
at cylinder 20 (the previous request served was at cylinder 19) when the last of these requests is made
with none of these requests yet served. The queue of pending requests, in FIFO order, is 5, 25, 18, 3,
39, 8, and 35. A seek takes 5ms per cylinder movement. Starting from the current head position, what
is the total distance (in cylinders) that the disk arm moves to satisfy all the pending request and alsocalculate the total seek time needed to serve these requests, for each of the following disk-scheduling
a. FCFS
b. SSTF
c. SCAN
d. LOOK
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