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Consider a disk queue with requests for I/O to blocks on cylinders 98, 183, 41, 122, 14, 124, 65, 67. The FCFS and SCAN scheduling algorithm is used. The head is initially at cylinder number 53. The cylinders are numbered from 0 to 199. Explain how these requests will be served and also draw the graph how the requests will be served.?
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Consider a disk queue with requests for I/O to blocks on cylinders 98,...
FCFS (First-Come, First-Served) Scheduling Algorithm:

In the FCFS scheduling algorithm, the requests are served in the order they arrive. The head starts at cylinder number 53 and serves the requests sequentially.

Step 1: The initial position of the head is at cylinder number 53.

Step 2: The head moves towards the first request at cylinder 98 and serves it.

Step 3: The head moves towards the next request at cylinder 183 and serves it.

Step 4: The head moves towards the next request at cylinder 41 and serves it.

Step 5: The head moves towards the next request at cylinder 122 and serves it.

Step 6: The head moves towards the next request at cylinder 14 and serves it.

Step 7: The head moves towards the next request at cylinder 124 and serves it.

Step 8: The head moves towards the next request at cylinder 65 and serves it.

Step 9: The head moves towards the last request at cylinder 67 and serves it.

Step 10: All requests have been served.

SCAN Scheduling Algorithm:

In the SCAN scheduling algorithm, the head starts at the current position and moves in one direction (either towards the lower-numbered cylinders or towards the higher-numbered cylinders) until it reaches the end of the disk. Then, it reverses direction and continues serving requests in the opposite direction.

Step 1: The initial position of the head is at cylinder number 53.

Step 2: The head moves towards the higher-numbered cylinders and serves the requests in that direction until it reaches the end of the disk.

Step 3: The head reaches the highest numbered cylinder (199) and reverses direction.

Step 4: The head moves towards the lower-numbered cylinders and serves the requests in that direction.

Step 5: The head reaches the lowest numbered cylinder (0) and stops serving requests.

Graphical Representation:
Below is the graphical representation of how the requests will be served using both FCFS and SCAN scheduling algorithms:

FCFS:
- Cylinder 53 -> 98 -> 183 -> 41 -> 122 -> 14 -> 124 -> 65 -> 67

SCAN:
- Cylinder 53 -> 65 -> 67 -> 98 -> 122 -> 124 -> 183 -> 199 -> 14 -> 0

Note: In the SCAN scheduling algorithm, the direction of movement of the head can be towards the lower-numbered cylinders as well, depending on the specific implementation. The above example assumes movement towards the higher-numbered cylinders.
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Consider a storage disk with 4 platters (numbered as 0, 1, 2 and 3), 200 cylinders (numbered as 0, 1, … , 199), and 256 sectors per track (numbered as 0, 1, … 255). The following 6 disk requests of the form [sector number, cylinder number, platter number] are received by the disk controller at the same time: [120, 72, 2], [180, 134, 1], [60, 20, 0], [212, 86, 3], [56, 116, 2], [118, 16, 1] Currently head is positioned at sector number 100 of cylinder 80, and is moving towards higher cylinder numbers. The average power dissipation in moving the head over 100 cylinders is 20 milliwatts and for reversing the direction of the head movement once is 15 milliwatts. Power dissipation associated with rotational latency and switching of head between different platters is negligible. The total power consumption in milliwatts to satisfy all of the above disk requests using the Shortest Seek Time First disk scheduling algorithm is ______ .Note -This was Numerical Type question.

Consider a storage disk with 4 platters (numbered as 0, 1, 2 and 3), 200 cylinders (numbered as 0, 1, … , 199), and 256 sectors per track (numbered as 0, 1, … , 255). The following 6 disk requests of the form [sector number, cylinder number, platter number] are received by the disk controller at the same time: [120, 72, 2] , [180, 134, 1] , [60, 20, 0] , [212, 86, 3] , [56, 116, 2] , [118, 16, 1] Currently the head is positioned at sector number 100 of cylinder 80, and is moving towards higher cylinder numbers. The average power dissipation in moving the head over 100 cylinders is 20 milliwatts and for reversing the direction of the head movement once is 15 milliwatts. Power dissipation associated with rotational latency and switching of head between different platters is negligible. The total power consumption in milliwatts to satisfy all of the above disk requests using the Shortest Seek Time First disk scheduling algorithm is _______. Correct answer is '85'. Can you explain this answer?

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Consider a disk queue with requests for I/O to blocks on cylinders 98, 183, 41, 122, 14, 124, 65, 67. The FCFS and SCAN scheduling algorithm is used. The head is initially at cylinder number 53. The cylinders are numbered from 0 to 199. Explain how these requests will be served and also draw the graph how the requests will be served.?
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Consider a disk queue with requests for I/O to blocks on cylinders 98, 183, 41, 122, 14, 124, 65, 67. The FCFS and SCAN scheduling algorithm is used. The head is initially at cylinder number 53. The cylinders are numbered from 0 to 199. Explain how these requests will be served and also draw the graph how the requests will be served.? 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 queue with requests for I/O to blocks on cylinders 98, 183, 41, 122, 14, 124, 65, 67. The FCFS and SCAN scheduling algorithm is used. The head is initially at cylinder number 53. The cylinders are numbered from 0 to 199. Explain how these requests will be served and also draw the graph how the requests will be served.? 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 queue with requests for I/O to blocks on cylinders 98, 183, 41, 122, 14, 124, 65, 67. The FCFS and SCAN scheduling algorithm is used. The head is initially at cylinder number 53. The cylinders are numbered from 0 to 199. Explain how these requests will be served and also draw the graph how the requests will be served.?.
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