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Andrew S. Tanenbaum (OS) Edition 4 Exercise 1 Question 24 (Page No. 83)

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Suppose that a $10$-MB file is stored on a disk on the same track (track $50$) in consecutive sectors. The disk arm is currently situated over track number $100$. How long will it take to retrieve this file from the disk? Assume that it takes about $1$ ms to move the arm from one cylinder to the next and about $5$ ms for the sector where the beginning of the file is stored to rotate under the head. Also, assume that reading occurs at a rate of $200$ MB/s.
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Time to retrieve the file = 1 * 50 ms (Time to move the arm over track 50) + 5 ms (Time for the first sector to rotate under the head) + 10/200 * 1000 ms (Read 10 MB) = 105 ms
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