C-SCAN Disk Scheduling Algorithm
The C-SCAN algorithm, also known as the Circular Elevator algorithm is the modified version of the SCAN algorithm. In this algorithm, the head pointer starts from one end of the disk and moves towards the other end, serving all requests in between. After reaching the other end, the head reverses its direction and goes to the starting point. It then satisfies the remaining requests, in the same direction as before. Unlike SSTF, it can handle requests only in one direction.
Example – Consider a disk with 200 tracks (0-199) and the disk queue having I/O requests in the following order as follows:
98, 183, 40, 122, 10, 124, 65
The current head position of the Read/Write head is 53 and will move in the right direction. Calculate the total number of track movements of the Read/Write head using the C-SCAN algorithm. Total head movements,
= (65-53)+(98-65)+(122-98)+(124-122)+(183-124)
+(199-183)+(199-0)+(10-0)+(40-10)
= 395
Difference Between C-SCAN and SSTF Disk Scheduling Algorithm
In C-SCAN Algorithm it is necessary to take into account the direction, i.e., larger or smaller value. This algorithm serves disk requests by moving towards their conclusion while SSTF is a secondary storage scheduling method that decides how the disk’s head and arm will move to fulfil read and write requests. In this article, you will discover the distinction between the SSTF and C-SCAN disk scheduling algorithms in this post. However, you must first understand the distinctions between the SSTF and C-SCAN disk scheduling algorithms.
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