Computer Science - Operating Systems Concepts - Discussion
Discussion Forum : Operating Systems Concepts - Section 2 (Q.No. 33)
33.
A disk scheduling algorithm in an operating system causes the disk arm to move back and forth across the disk surface in order to service all requests in its path. This is a
Discussion:
6 comments Page 1 of 1.
Shreyash Lavate said:
5 years ago
Disk Scheduling Algorithms.
1) FCFS - Requests are addressed in the order they arrive.
2) SSTF- just like shortest job first, the request with shortest seek time (time required to locate data) are executed first. Seek time of requests is calculated and accordingly scheduled.
3) SCAN- disk arm will move in a particular direction and addresses requests in its path after reaching the end of the disk, it reverses it's direction and repeats the previous process also known as elevator algorithm.
4) LOOK- similar to scan except for disk arm in spite reaching end of the disk goes to the last request to be addressed in the front of the head and then reverses its direction. It prevents extra delay due to unnecessary traversal to disk end.
1) FCFS - Requests are addressed in the order they arrive.
2) SSTF- just like shortest job first, the request with shortest seek time (time required to locate data) are executed first. Seek time of requests is calculated and accordingly scheduled.
3) SCAN- disk arm will move in a particular direction and addresses requests in its path after reaching the end of the disk, it reverses it's direction and repeats the previous process also known as elevator algorithm.
4) LOOK- similar to scan except for disk arm in spite reaching end of the disk goes to the last request to be addressed in the front of the head and then reverses its direction. It prevents extra delay due to unnecessary traversal to disk end.
(1)
Yashika said:
8 years ago
Yes, you are right. @Gokul.
Gokul said:
8 years ago
Answer: A.
In the SCAN algorithm, the disk arm starts at one end of the disk and moves.
Toward the other end, servicing requests as it reaches each cylinder, until it gets to the other end of the disk.
In First come first served, the disk arm to move back and forth according to the request. Comparatively it as the most disk movement.
In the SCAN algorithm, the disk arm starts at one end of the disk and moves.
Toward the other end, servicing requests as it reaches each cylinder, until it gets to the other end of the disk.
In First come first served, the disk arm to move back and forth according to the request. Comparatively it as the most disk movement.
E J said:
9 years ago
What is scan algorithm? Please describe it.
Riva said:
1 decade ago
What is scan algorithm?
Taher ali said:
1 decade ago
In Scan algorithm the disk arm starts at one end of the disk and moves toward the other end, servicing requests as it reaches each cylinder, until it gets to the other end of the disk.
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