Explain Concurrent Sharing
Here a number of programs that may share a file simultaneously. While this is the case, it is necessary to prevent mutual interference among them. There are three types of concurrent sharing:
1. Immutable files: If a file is shared in immutable mode, none of the sharing programs can alter it. This mode has the benefit that sharing programs are independent of one another.
2. Single image immutable files: Here the modifications made by one program are instantaneously visible to other programs. The UNIX file system employs this file-sharing mode.
3. Multiple image mutable files: Here several programs can concurrently update the shared file. Each updating program makes a new version of the file that is different from the version made by concurrent programs.
This sharing mode can just only be used in applications in which concurrent updates and the existence of several versions are meaningful.