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Consider a disk system having 60 cylinders. Disk requests are received by a disk drive for cylinders 10, 22, 20, 2, 40, 6, and 38, in that order. Assuming the disk head is currently at cylinder 20, what is the time taken to satisfy all the requests if it takes 2 milliseconds to move from one cylinder to an adjacent one and Shortest Seek Time First (SSTF) algorithm is used ?
- a)240 milliseconds
- b)96 milliseconds
- c)120 milliseconds
- d)112 milliseconds
Correct answer is option 'C'. Can you explain this answer?
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Most Upvoted Answer
Consider a disk system having 60 cylinders. Disk requests are received...
Shortest Seek Time First (SSTF)
SSTF =(22-20+22-10+10-6+6-2+38-2+40-38)
=2+12+4+4+36+2
=60
=2+12+4+4+36+2
=60
It takes 2 milliseconds to move from one cylinder to adjacent one = 60x2 =120 milliseconds
∴ Hence the correct answer is 120 milliseconds.
∴ Hence the correct answer is 120 milliseconds.
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Community Answer
Consider a disk system having 60 cylinders. Disk requests are received...
Given:
- Disk system has 60 cylinders.
- Disk requests are received for cylinders 10, 22, 20, 2, 40, 6, and 38.
- Disk head is currently at cylinder 20.
- It takes 2 milliseconds to move from one cylinder to an adjacent one.
- Shortest Seek Time First (SSTF) algorithm is used.
To find:
- Time taken to satisfy all the requests.
Approach:
1. Calculate the distance between the current cylinder and each requested cylinder.
2. Select the cylinder with the shortest seek time (distance) from the current cylinder.
3. Move the disk head to the selected cylinder and calculate the seek time.
4. Repeat steps 2 and 3 until all requests are satisfied.
5. Sum the seek times to find the total time taken.
Calculation:
- Current cylinder: 20
- Requests: 10, 22, 20, 2, 40, 6, 38
1. Distance calculation:
- Distance from 20 to 10 = |20 - 10| = 10
- Distance from 20 to 22 = |20 - 22| = 2
- Distance from 20 to 20 = 0
- Distance from 20 to 2 = |20 - 2| = 18
- Distance from 20 to 40 = |20 - 40| = 20
- Distance from 20 to 6 = |20 - 6| = 14
- Distance from 20 to 38 = |20 - 38| = 18
2. Shortest Seek Time First (SSTF) algorithm:
- Select 2 (shortest distance from 20)
- Seek time = 2 milliseconds
- Move to cylinder 2
3. Distance calculation:
- Distance from 2 to 10 = |2 - 10| = 8
- Distance from 2 to 22 = |2 - 22| = 20
- Distance from 2 to 20 = |2 - 20| = 18
- Distance from 2 to 40 = |2 - 40| = 38
- Distance from 2 to 6 = |2 - 6| = 4
- Distance from 2 to 38 = |2 - 38| = 36
4. Shortest Seek Time First (SSTF) algorithm:
- Select 6 (shortest distance from 2)
- Seek time = 4 milliseconds
- Move to cylinder 6
5. Distance calculation:
- Distance from 6 to 10 = |6 - 10| = 4
- Distance from 6 to 22 = |6 - 22| = 16
- Distance from 6 to 20 = |6 - 20| = 14
- Distance from 6 to 40 = |6 - 40| = 34
- Distance from 6 to 38 = |6 - 38| = 32
6. Shortest Seek Time First (SSTF) algorithm:
- Select 10 (shortest distance from 6)
- Seek time = 4 milliseconds
- Move to cylinder 10
7. Distance calculation:
- Distance
- Disk system has 60 cylinders.
- Disk requests are received for cylinders 10, 22, 20, 2, 40, 6, and 38.
- Disk head is currently at cylinder 20.
- It takes 2 milliseconds to move from one cylinder to an adjacent one.
- Shortest Seek Time First (SSTF) algorithm is used.
To find:
- Time taken to satisfy all the requests.
Approach:
1. Calculate the distance between the current cylinder and each requested cylinder.
2. Select the cylinder with the shortest seek time (distance) from the current cylinder.
3. Move the disk head to the selected cylinder and calculate the seek time.
4. Repeat steps 2 and 3 until all requests are satisfied.
5. Sum the seek times to find the total time taken.
Calculation:
- Current cylinder: 20
- Requests: 10, 22, 20, 2, 40, 6, 38
1. Distance calculation:
- Distance from 20 to 10 = |20 - 10| = 10
- Distance from 20 to 22 = |20 - 22| = 2
- Distance from 20 to 20 = 0
- Distance from 20 to 2 = |20 - 2| = 18
- Distance from 20 to 40 = |20 - 40| = 20
- Distance from 20 to 6 = |20 - 6| = 14
- Distance from 20 to 38 = |20 - 38| = 18
2. Shortest Seek Time First (SSTF) algorithm:
- Select 2 (shortest distance from 20)
- Seek time = 2 milliseconds
- Move to cylinder 2
3. Distance calculation:
- Distance from 2 to 10 = |2 - 10| = 8
- Distance from 2 to 22 = |2 - 22| = 20
- Distance from 2 to 20 = |2 - 20| = 18
- Distance from 2 to 40 = |2 - 40| = 38
- Distance from 2 to 6 = |2 - 6| = 4
- Distance from 2 to 38 = |2 - 38| = 36
4. Shortest Seek Time First (SSTF) algorithm:
- Select 6 (shortest distance from 2)
- Seek time = 4 milliseconds
- Move to cylinder 6
5. Distance calculation:
- Distance from 6 to 10 = |6 - 10| = 4
- Distance from 6 to 22 = |6 - 22| = 16
- Distance from 6 to 20 = |6 - 20| = 14
- Distance from 6 to 40 = |6 - 40| = 34
- Distance from 6 to 38 = |6 - 38| = 32
6. Shortest Seek Time First (SSTF) algorithm:
- Select 10 (shortest distance from 6)
- Seek time = 4 milliseconds
- Move to cylinder 10
7. Distance calculation:
- Distance
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Consider a disk system having 60 cylinders. Disk requests are received by a disk drive for cylinders 10, 22, 20, 2, 40, 6, and 38, in that order. Assuming the disk head is currently at cylinder 20, what is the time taken to satisfy all the requests if it takes 2 milliseconds to move from one cylinder to an adjacent one and Shortest Seek Time First (SSTF) algorithm is used ?a)240 millisecondsb)96 millisecondsc)120 millisecondsd)112 millisecondsCorrect answer is option 'C'. Can you explain this answer?
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Consider a disk system having 60 cylinders. Disk requests are received by a disk drive for cylinders 10, 22, 20, 2, 40, 6, and 38, in that order. Assuming the disk head is currently at cylinder 20, what is the time taken to satisfy all the requests if it takes 2 milliseconds to move from one cylinder to an adjacent one and Shortest Seek Time First (SSTF) algorithm is used ?a)240 millisecondsb)96 millisecondsc)120 millisecondsd)112 millisecondsCorrect answer is option 'C'. Can you explain this answer? for Computer Science Engineering (CSE) 2024 is part of Computer Science Engineering (CSE) preparation. The Question and answers have been prepared according to the Computer Science Engineering (CSE) exam syllabus. Information about Consider a disk system having 60 cylinders. Disk requests are received by a disk drive for cylinders 10, 22, 20, 2, 40, 6, and 38, in that order. Assuming the disk head is currently at cylinder 20, what is the time taken to satisfy all the requests if it takes 2 milliseconds to move from one cylinder to an adjacent one and Shortest Seek Time First (SSTF) algorithm is used ?a)240 millisecondsb)96 millisecondsc)120 millisecondsd)112 millisecondsCorrect answer is option 'C'. Can you explain this answer? covers all topics & solutions for Computer Science Engineering (CSE) 2024 Exam. Find important definitions, questions, meanings, examples, exercises and tests below for Consider a disk system having 60 cylinders. Disk requests are received by a disk drive for cylinders 10, 22, 20, 2, 40, 6, and 38, in that order. Assuming the disk head is currently at cylinder 20, what is the time taken to satisfy all the requests if it takes 2 milliseconds to move from one cylinder to an adjacent one and Shortest Seek Time First (SSTF) algorithm is used ?a)240 millisecondsb)96 millisecondsc)120 millisecondsd)112 millisecondsCorrect answer is option 'C'. Can you explain this answer?.
Consider a disk system having 60 cylinders. Disk requests are received by a disk drive for cylinders 10, 22, 20, 2, 40, 6, and 38, in that order. Assuming the disk head is currently at cylinder 20, what is the time taken to satisfy all the requests if it takes 2 milliseconds to move from one cylinder to an adjacent one and Shortest Seek Time First (SSTF) algorithm is used ?a)240 millisecondsb)96 millisecondsc)120 millisecondsd)112 millisecondsCorrect answer is option 'C'. Can you explain this answer? for Computer Science Engineering (CSE) 2024 is part of Computer Science Engineering (CSE) preparation. The Question and answers have been prepared according to the Computer Science Engineering (CSE) exam syllabus. Information about Consider a disk system having 60 cylinders. Disk requests are received by a disk drive for cylinders 10, 22, 20, 2, 40, 6, and 38, in that order. Assuming the disk head is currently at cylinder 20, what is the time taken to satisfy all the requests if it takes 2 milliseconds to move from one cylinder to an adjacent one and Shortest Seek Time First (SSTF) algorithm is used ?a)240 millisecondsb)96 millisecondsc)120 millisecondsd)112 millisecondsCorrect answer is option 'C'. Can you explain this answer? covers all topics & solutions for Computer Science Engineering (CSE) 2024 Exam. Find important definitions, questions, meanings, examples, exercises and tests below for Consider a disk system having 60 cylinders. Disk requests are received by a disk drive for cylinders 10, 22, 20, 2, 40, 6, and 38, in that order. Assuming the disk head is currently at cylinder 20, what is the time taken to satisfy all the requests if it takes 2 milliseconds to move from one cylinder to an adjacent one and Shortest Seek Time First (SSTF) algorithm is used ?a)240 millisecondsb)96 millisecondsc)120 millisecondsd)112 millisecondsCorrect answer is option 'C'. Can you explain this answer?.
Solutions for Consider a disk system having 60 cylinders. Disk requests are received by a disk drive for cylinders 10, 22, 20, 2, 40, 6, and 38, in that order. Assuming the disk head is currently at cylinder 20, what is the time taken to satisfy all the requests if it takes 2 milliseconds to move from one cylinder to an adjacent one and Shortest Seek Time First (SSTF) algorithm is used ?a)240 millisecondsb)96 millisecondsc)120 millisecondsd)112 millisecondsCorrect answer is option 'C'. Can you explain this answer? in English & in Hindi are available as part of our courses for Computer Science Engineering (CSE).
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ample number of questions to practice Consider a disk system having 60 cylinders. Disk requests are received by a disk drive for cylinders 10, 22, 20, 2, 40, 6, and 38, in that order. Assuming the disk head is currently at cylinder 20, what is the time taken to satisfy all the requests if it takes 2 milliseconds to move from one cylinder to an adjacent one and Shortest Seek Time First (SSTF) algorithm is used ?a)240 millisecondsb)96 millisecondsc)120 millisecondsd)112 millisecondsCorrect answer is option 'C'. Can you explain this answer? tests, examples and also practice Computer Science Engineering (CSE) tests.
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