Which of the following statements about disk scheduling algorithms is correct?

2022

Which of the following statements about disk scheduling algorithms is correct?

  1. A.

    The disk arm behaves like an elevator in SCAN algorithm. SCAN

  2. B.

    FCFS provides fastest service to the disk requests. FCFS

  3. C.

    SSTF algorithm is an optimal algorithm. SSTF

  4. D.

    SCAN algorithm provides more uniform wait time compared to C-SCAN algorithm. SCAN, C-SCAN

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Correct answer: A

The SCAN algorithm is also called the Elevator algorithm because the disk arm moves in one direction servicing requests, then reverses direction—just like an elevator. FCFS is simple but not the fastest. SSTF is not optimal and may cause starvation. C-SCAN generally provides more uniform wait time than SCAN, not the other way around.

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