Question

Given that it takes 0.08 ms to travel from one track to the next of a hard drive; that the arm is originally positioned at Track 15 moving toward the low-numbered tracks; and that you are using the LOOK scheduling policy: Compute the total seek time to satisfy the following requests-4, 40, 35, 11, 14, and 7. Assume all requests are initially present in the wait queue. (Ignore rotational time and transfer time; just consider seek time.)

Answer 1

Answer:

Time taken to travel from one track to the next = 0.08ms

Initial track= 15     0

4      (15-4)*(0.08)= 0.88

40     (40-4)*(0.08)= 2.88

35      (40-35)*(0.08)= 0.4

11       (35-11)*(0.08)= 1.92

14       (14-11)*(0.08)= 0.24

7         (14-7)*(0.08)= 0.56

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Total seek time=0.88+2.88+0.4+1.92+0.24+0.56=6.88ms

Explanation:

We caculate the seek time for each request, and then add them together to find the total seek time. The final track number for the current request becomes the current track of next request, and this process is repeated till the last request is processed.