Question

A disk has 128 tracks of 32 sectors each, on each surface of eight platters. The disk spins at 3600 RPM and takes 15 ms to move between adjacent tracks. What is the longest time needed to read an arbitrary sector located anywhere on the disk

Answer 1

Answer:

the longest time needed to read an arbitrary sector located anywhere on the disk is 2971.24 ms

Explanation:

 Given the data in the question;

first we determine the rotational latency

Rotational latency = 60/(3600×2) = 0.008333 s = 8.33 ms

To get the longest time, lets assume the sector will be found at the last track.

hence we will access all the track, meaning that 127 transitions will be done;

so the track changing time = 127 × 15 = 1905 ms

also, we will look for the sectors, for every track rotations that will be done;

128 × 8.33 = 1066.24 ms

∴The Total Time = 1066.24 ms + 1905 ms

Total Time = 2971.24 ms

Therefore, the longest time needed to read an arbitrary sector located anywhere on the disk is 2971.24 ms