A hard disk spins at 6000 rpm (revolutions per minute), and it takes 100 μs (on average) for the head to traverse one track. Consider the following sequence of disk track requests: 27, 129, 110, 186, 147, 41, 10, 64, 120. Assume that initially the head is at track 30 and is moving in the direction of decreasing track numbers. Compute the time it takes to serve the requests using (1) FIFO, (2) SSF (Shortest-Seek First), (3) SCAN.
I understand the difference between the different algorithms and I generally get how to calculate it.
My questions is, when I calculate the Average rotational time, i.e. (60/6000) / 2 = 5ms, do I need to multiply this by the number of tracks moved?
My FIFO calculation as an example:
(3+102+19+76+39+106+31+54+56) * (5ms + 0.1ms) = 2478.6ms
I add up the number of tracks moved and multiply this by the average rotational time + the time it takes to traverse each track.
Is this approach correct?