Disk Scheduling

FCFS Scheduling

The simplest disk scheduling algorithm is First Come First Serve Scheduling algorithm.

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SSTF Scheduling

SSTF stands for Shortest Seek Time First algorithm. The SSTF selects the request that have smallest seek time from the current head position. The algorithm have better performace over FCFS scheduling algorithm

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SCAN Scheduling

In SCAN algorithm, disk arm starts moving from one end of the disk to other end. While moving, it services along the way. On reaching other end, direction of head movement is reversed and while coming back, it again services the request in the path. This algorithm is also known as elevator algorithm.

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C-SCAN Scheduling

C-SCAN stands for Circular SCAN Scheduling. In this scheduling algorithm like SCAN algorithm, head moves from one end to other and services the request  along the way. But on reaching the other end, the head immediately returns to the beginning of the disk without service request while coming back.

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