$1.$ Given a disk with $120$ tracks with the read$/$write head originally positioned at track $5,$ compute the total and average track traversals to satisfy the following requests using FCFS$,$ SSTF$,$ SCAN and C$-$SCAN.

$14,1,97,30,111,27,6,48$

Draw the corresponding diagram showing the movement of the read$/$write head in each case.

Using FCFS$-$or FIFO Policy as listed in the notes$-$ to compute the total and average track traversals, the disk read$/$write head goes from number to number as in the above stated sequence handling each request as it goes along.

From $5$ to $14$: $.....$ tracks traversed

From $1$ to $97$: $.....$ tracks traversed

From $30$ to $111$: $81....$ tracks traversed

From $27$ to $6$: $....$ tracks traversed

Totaling: $9$ tracks

$..$tracks traversed for the average request

Using SSTF to compute the total and average track traversals, the disk read$/$write head goes the shortest seek time from its position. The queue is re$-$ordered as a result.

$14,1,97,30,111,27,6,48------6,1,14,27,30,48,97,111$re$-$ordered queue

Using SCAN Policy to compute the total and average track traversals, the read$/$write head is moves towards the highest numbered track, picking up requests as it goes along. It then scans the other direction towards the lowest numbered track, again picking up requests as it proceeds.

$14,1,97,30,111,27,6,48...$re$-$ordered queue$-161427304897111$

Using C$-$SCAN Policy to compute the total and average track traversals, the read$/$write head is moves in one direction only processing requests as it goes along. It then goes back to the beginning and restarts when the end is reached

$14,1,97,30,111,27,6,48...$re$-$ordered queue$-614273048971111$