In __________ disk scheduling algorithm, the disk head moves from one end to…
2017
In __________ disk scheduling algorithm, the disk head moves from one end to other end of the disk, serving the requests along the way. When the head reaches the other end, it immediately returns to the beginning of the disk without serving any requests on the return trip.
- A.
LOOK
- B.
SCAN
- C.
C - LOOK
- D.
C - SCAN
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Correct answer: D
Correct answer: C - SCAN
Explanation: C-SCAN (Circular SCAN) moves the disk head in one direction from one end of the disk to the other, servicing all requests encountered along that direction. When the head reaches the far end, it returns to the beginning of the disk without servicing requests during the return trip (it effectively wraps around) and then continues servicing in the same direction.
Serves requests only while moving in the chosen direction; the return is a rapid repositioning without service.
Provides more uniform wait times compared with SCAN because every request is served while the head moves in the same direction.
Contrast with SCAN: SCAN reverses direction and continues servicing requests on the return trip, so it does not match the behavior described in the question.
Therefore, the described algorithm is C-SCAN (circular SCAN), which matches the behavior of moving end-to-end and returning to the start without serving requests on the return.
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