Os Process Management Questions Medium
There are several disk scheduling algorithms used in operating systems to optimize the disk access and improve overall system performance. Some of the commonly used disk scheduling algorithms are:
1. First-Come, First-Served (FCFS): In this algorithm, the requests are served in the order they arrive. It is a simple and easy-to-implement algorithm but may result in poor performance due to the lack of consideration for the location of the requested data.
2. Shortest Seek Time First (SSTF): This algorithm selects the request with the shortest seek time from the current head position. It aims to minimize the total seek time and provides better performance compared to FCFS. However, it may lead to starvation for requests located far from the current head position.
3. SCAN: The SCAN algorithm moves the disk arm from one end of the disk to the other, serving all the requests in its path. After reaching the end, it reverses direction and serves the remaining requests in the opposite direction. This algorithm provides a fair distribution of service but may result in increased waiting time for requests located at the ends of the disk.
4. Circular SCAN (C-SCAN): C-SCAN is an improved version of the SCAN algorithm. It works similar to SCAN but instead of reversing direction at the end, it jumps to the other end of the disk and starts serving requests from there. This eliminates the increased waiting time for requests at the ends of the disk.
5. LOOK: The LOOK algorithm is similar to SCAN, but it only serves the requests in the current direction of the disk arm. Once there are no more requests in that direction, it reverses direction and starts serving requests from the other end. This reduces the unnecessary movement of the disk arm and improves performance compared to SCAN.
6. C-LOOK: C-LOOK is an improved version of the LOOK algorithm. It works similar to LOOK but instead of reversing direction at the end, it jumps to the other end of the disk and starts serving requests from there. This eliminates the unnecessary movement of the disk arm and provides better performance.
These disk scheduling algorithms aim to minimize the seek time, reduce the waiting time, and improve the overall efficiency of disk access in operating systems. The choice of algorithm depends on the specific requirements and characteristics of the system.