contiguous allocation - TarisMajor/5143-OpSystems GitHub Wiki
Contiguous allocation is a file storage method in which a file is stored in consecutive blocks of memory. This approach is straightforward and provides efficient access to file data, but it also comes with some challenges.
- Continuous Blocks: Files are stored in a series of consecutive blocks on the disk. This means that all the blocks allocated to a file are adjacent to each other.
- Fixed Size: When a file is created, a fixed amount of contiguous space is allocated based on the file's expected size.
- Sequential Access: This allocation method is highly efficient for sequential access, as the file can be read from start to finish without jumping between non-contiguous blocks.
- Fast Access: Since files are stored in contiguous blocks, access times are reduced. The read/write head of the disk can move smoothly over the blocks, minimizing seek times.
- Simple Implementation: The method is simple to implement and understand, making it easy to manage within the file system.
- Ease of Access: File data can be accessed quickly and efficiently, especially for sequential reads and writes.
- Fragmentation: Over time, as files are created and deleted, the disk can become fragmented. This makes it difficult to find contiguous blocks of space for new files, leading to wasted space and decreased performance.
- Fixed Size Allocation: Allocating a fixed size at the time of file creation can lead to wasted space if the file size is overestimated or the need to move files if the size is underestimated.
- Limited Flexibility: Growing a file beyond its allocated space requires finding a new contiguous block of sufficient size, which can be challenging on a fragmented disk.
- Read-Only Media: Ideal for read-only media such as CDs and DVDs, where files do not change, and fragmentation is not an issue.
- Sequential Access Files: Suitable for applications that primarily access files sequentially, such as multimedia files (audio, video) and large data sets.
- Simple File Systems: Useful in simple file systems where the ease of implementation and fast access times are more critical than dealing with fragmentation.