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Exercise 3 - Disk Operation

Estimate the average time to access a sector in a disk which parameters are given below.
Rotational speed 12000 RPM
Avg No of sector/track 500
Avg seek time 8 ms

Solution
Avg access time = Avg seek time + Avg rotation time + Avg transfer time

Avg rotation time = 1/2 x (Max. rotation time) = 1/2 x (60 sec/12000 rpm) x 1000 ms = 2.5 ms

Avg transfer time = (60 sec/12000 rpm) x (1/500) x 1000 ms = 0.01 ms

Avg access time = 8 ms + 2.5 ms + 0.01 ms = 10.51 ms

The average time to access a sector is 10.51 ms
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