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Consider a disk system with 100 cylinders. The requests to access the cylinders occur in following sequence 4, 34, 10, 7, 19, 73, 2, 15, 6, 20 Assuming that the head is currently at cylinder 50, what is the time taken to satisfy requests, if it takes 1 ms to move from one cylinder to adjacent one and shortest seek time first policy is used?
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- 95 ms
- 119 ms
- 233 ms
- 276 ms
- 95 ms
Correct Option: B
Requests | 4 | 34 | 10 | 7 |
19 73 | 2 | 15 | 6 | 20 |
Current | 50 | 34 | 20 | 19 |
15 10 | 7 | 6 | 4 | 2 |
Next access | 34 | 20 | 19 | 15 |
10 7 | 6 | 4 | 2 | 73 |
Difference | 16 | 14 | 1 | 4 |
5 3 | 1 | 2 | 2 | 71 |
Therefore, total moves = 16 + 14 + 1 + 4 + 5 + 3 + 1 + 2 + 2 + 71 = 119 ms