Question :

The file system is the most visible aspect of an operating system. It provides the mechanism for on-line storage and access to both data and programs of the operating system and to all the users of the computer system.

(a) What is a file?

(b) Many systems require and open system call and a close system call. Explain the purpose of the open and close operations.

(c) Some systems automatically open a file when it is referenced for the first time, and close the file when the job terminates. What is the advantage and disadvantage of this scheme as compared to the more traditional one, where the user has to open and close the file explicitly?

(d) Just as a file must be opened before it is used, a file system must be mounted before it can be available to processes in the system. Describe the mount procedure that is performed by the operating system.

(e) Consider a file system where a file can be deleted and its disk space reclaimed while links to that file still exists.

I. What problems may occur if a new file is created in the same storage area or with same absolute path name?

II. How can these problems be avoided?