SCAN and CSCAN Algorithm

Question

I find it difficult to understand how the SCAN and CSCAN algorithm work for disk planning. I realized that FCFS, the closest cylinder to Next, but I heard that SCAN resembled the elevator mechanism and got confused. My book says that for an incoming order: [10 22 20 2 40 6 38] (while the drive is currently at 20) SCAN, moving at the beginning, serves [(20) 20 22 38 40 10 6 2]; this requires cylinder strokes [0 2 16 2 30 4 4], for a total of 58 cylinders. How did the template [(20) 20 22 38 40 10 6 2] appear?

Answer 1

Know what the SCAN Disk Dispatch Algorithm (Elevator) says: -

, , , . , , .

, 20. , SCAN, , .

: -

|                                                     |


| * current position                                  | * move back up to upside
|---> nearest disk is this one                        |
|     so it'll move down and so on.                   |
|         as it hit the bottom                     _______

____

                   Fig :- Demonstration of SCAN algorithm  

, , [(20) 20 22 38 40 10 6 2];

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: -

SCAN CSCAN , CSCAN

. , , SCAN, , .

CSCAN , .

, , [(20) 20 22 38 40 2 6 10]; .

, . .