|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.
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|