The First-Come, First-Served (FCFS) disk scheduling algorithm is a straightforward and simple method for scheduling disk requests in computer systems. As the name suggests, this algorithm services disk requests in the order in which they are received, without considering the location of the disk head or the proximity of the disk requests.
The basic idea behind the FCFS disk scheduling algorithm is that it prioritizes disk requests based on the order in which they are received. This means that the first disk request to arrive is the first disk request to be serviced, and so on.
To implement the FCFS disk scheduling algorithm, we first need to keep track of the current position of the disk head. This can be done using a simple variable that stores the current position of the disk head on the disk.
Next, we need to keep track of the list of disk requests. This can be done using a data structure such as an array or a linked list. Each entry in the list should include the disk request's cylinder number.
Once we have our list of disk requests, we can begin the process of selecting the disk request to be serviced next. This can be done using a simple loop that iterates over the list of disk requests and selects the next disk request in the list.
After the disk request has been serviced, we need to update the current position of the disk head and the list of disk requests. The current position of the disk head should be updated to the cylinder number of the disk request that was just serviced, and the disk request should be removed from the list of disk requests.
The process of selecting and servicing disk requests then repeats until all disk requests have been serviced. At this point, the total seek time for all disk requests can be calculated and compared to other disk scheduling algorithms to determine the best approach for a given set of disk requests.
The FCFS disk scheduling algorithm has several advantages over other disk scheduling algorithms. For example, it is easy to understand and implement, making it a good choice for systems with simple disk request patterns. Additionally, it is a fair and predictable algorithm, as disk requests are serviced in the order in which they are received.
However, the FCFS disk scheduling algorithm also has some disadvantages. For example, it is not well-suited for systems with a large number of disk requests, as the time required to seek the disk can become quite large. Additionally, it may not be the best choice for systems with heavy disk I/O, as it may not be able to keep up with the high number of disk requests.
In conclusion, the First-Come, First-Served (FCFS) disk scheduling algorithm is a straightforward and simple method for scheduling disk requests in computer systems. It is easy to understand and implement, and provides a fair and predictable approach to disk scheduling. However, it may not be the best choice for systems with a large number of disk requests or heavy disk I/O, as it may not be able to keep up with the high number of disk requests. When choosing a disk scheduling algorithm, it's important to consider the specific needs and requirements of your system, as well as the characteristics of your workload, to determine the best approach for your specific situation.
