Consider the following five disk five disk access requests of the form (request id, cylinder number) that are present in the disk scheduler queue at a given time.
(P,155), (Q,85), (R,110), (S,30), (T,115)
Assume the head is positioned at cylinder 100. The scheduler follows the Shortest Seek Time First scheduling to service the requests.
Which one of the following statements is FALSE?
T is serviced before P.
Q is serviced after S, but before T.
The head reverses its direction of movement between servicing of Q and P.
R is serviced before P.
Given
Arrange them in increasing order of cylinder number
(S, 30), (Q, 85), (Head - 100), (R, 110), (T, 115), (P, 155)
Diagrammatically:
Given that the scheduler follows the shortest seek time first scheduling to service the request, where the shortest seek time is the shortest time required by the read/write head to move from one track to another. Analyzing the diagram, we can deduce that option (B) is the only false statement.