Disk requests come to a disk driver for cylinders 10, 22, 20, 2, 40, 6 and 38, in that order at a time when the disk drive is reading from cylinder 20. The seek time is 6 ms per cylinder.
The total seek time, if the disk arm scheduling algorithm is first-come-first-served is
| A. | 360 ms |
| B. | 876 ms |
| C. | 850 ms |
| D. | 900 ms |
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Option: B Explanation : According to FCFS order serverd will be (20),10, 22, 20, 2, 40, 6 and 38 Seek time = 10+12+2+18+38+34+32 = 146 The disk drive has to traverse totally 146 cylinders (verify). So, seek time is 6 x 146 = 876 ms. Click on Discuss to view users comments. Kishore R said: (6:17pm on Friday 9th October 2015)
disk drive is reading from cylinder 20,fcfs ,20 2 40 6 38 10 22=138seek time=138x6=824 I had some confusion
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Disk requests come to a disk driver for cylinders 10, 22, 20, 2, 40, 6 and 38, in that order at a time when the disk drive is reading from cylinder 20. The seek time is 6 ms per cylinder.
If the scheduling algorithm is the closest cylinder next, then the total seek time will be
| A. | 360 ms |
| B. | 876 ms |
| C. | 850 ms |
| D. | 900 ms |
|
Option: A Explanation : Click on Discuss to view users comments. |
Disk sheduling involves deciding
| A. | which disk should be accessed next |
| B. | the order in which disk access requests must be serviced |
| C. | the physical location where files should be accessed in the disk |
| D. | none of these |
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Option: B Explanation : Click on Discuss to view users comments. |
Poor response time are caused by
| A. | Process or busy |
| B. | High I/O rate |
| C. | High paging rates |
| D. | All of these |
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Option: D Explanation : Click on Discuss to view users comments. |
A certain moving arm disk storage with one head has following specifications : Number of tracks I recording surface 100 Disk rotation speed 2400 rpm Track storage capacity= 62500 bits
The average latency time (assume the head can move from one track to another only by traversing the entire track) is
| A. | 2.5 s |
| B. | 2.9 s |
| C. | 3.1 s |
| D. | 3.6 s |
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Option: A Explanation :
In 60 seconds, the disk rotates 2400 times. So it takes 25ms to rotate it one time. Click on Discuss to view users comments. |
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