Question

Policy selects the disk I/O request that requires the least movement of the disk arm from its current position.

a. SSTF
b. LOOK
c. C-SCAN
d. SCAN

Answer 1

The disk scheduling policy that selects the request requiring the least movement of the disk arm is determined by different algorithms such as SSTF, LOOK, C-SCAN, and SCAN.

Step-by-step explanation:

The subject of this question is Computers and Technology. The question is asking about a disk scheduling policy that selects the disk I/O request requiring the least movement of the disk arm from its current position. The four options provided are:

1. SSTF (Shortest Seek Time First): This policy selects the request that is closest to the current arm position in terms of seek time, i.e., the request that requires the least movement of the arm. It minimizes the average seek time.
2. LOOK: This policy moves the arm towards the closest request in the current direction and scans inward until it reaches the last request, then reverses direction and scans outward. It does not move the arm beyond the last request in either direction, reducing unnecessary movement.
3. C-SCAN (Circular SCAN): This policy moves the arm towards the closest request in the current direction, scanning all requests in that direction and wrapping around to the beginning of the disk after reaching the end. It provides a more uniform response time compared to the LOOK policy.
4. SCAN: This policy moves the arm towards the closest request in the current direction, scanning all requests in that direction and then reverses direction to scan all requests in the opposite direction. It provides a more uniform response time compared to the SSTF policy.