Discussion Forum
Que. | Consider the input/output (I/O) requests made at different instants of time directed at a hypothetical disk having 200 tracks as given in the following table.
Assume that: Current head position is at track no. 65 Direction of last movement is towards higher numbered tracks Current clock time is 160 milliseconds Head movement time per track is 1 millisecond. “look” is a variant of “SCAN” disk-arm scheduling algorithm. In this algorithm, if no more I/O requests are left in current direction, the disk head reverses its direction. The seek times in Shortest Seek First (SSF) and “look” disk-arm scheduling algorithms respectively are: |
a. | 144 and 123 milliseconds |
b. | 143 and 123 milliseconds |
c. | 149 and 124 milliseconds |
d. | 256 and 186 milliseconds |
Answer:143 and 123 milliseconds |