SSTF Disk Scheduling Algorithm
SSTF stands for Shortest Seek Time First, as the name suggests it serves the request which is closest to the current position of head or pointer. In this algorithm, direction of the head pointer matters a lot. If there occurs a tie between requests, then the head will serve the request in its ongoing direction. Unlike C-SCAN, SSTF algorithm is very efficient in total seek time.
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
Current head position of the Read/Write head is 53 and will move in Right direction. Calculate the total number of track movements of Read/Write head using SSTF algorithm. Total head movements,
= (65-53)+(65-40)+(40-10)
+(98-10)+(122-98)+(124-122)+(183-124)
= 240
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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