Page 242 - DCAP103_Principle of operating system

Unit 6: File Management

Anonymous Access: The most common Web site access control method, allows anyone to visit Notes
the public areas of your Web sites.
Free-Space List: A list of unoccupied areas of memory in main or backing store. It is a special
case of an available list.

1. Assume 4 jobs arrive to a batch system at 10:00 am in the morning precisely
at the following moments:
Job 1: 10:00am (requires 4 minutes of CPU)
Job 2: 10:10am (requires 3 minutes of CPU)

Job 3: 10:15am (requires 2 minutes of CPU)
Job 4: 10:20am (requires 1 minute of CPU)
When does each job completes, If the probability of I/O is 0.8?

2. C Program For File Operations.
3. C Program For File Copy and Move.

6.15 Review Questions

1. What is a file?
2. What are the typical operations performed on files?
3. What are File Control Blocks?
4. What are file types?

5. How is free space managed?
6. Consider a file system where a file can be deleted and its disk space Reclaimed while links
to that file still exist. What problems may occur if a new file is created in the same storage
area or with the same absolute path name? How can these problems be avoided?

7. What are the advantages and disadvantages of a system providing mandatory locks instead
of providing advisory locks whose usage is left to the users’ discretion?

8. What are the advantages and disadvantages of recording the name of the creating program
with the file’s attributes (as is done in the Macintosh Operating System)?
9. If the operating system were to know that a certain application is going to access the
file data in a sequential manner, how could it exploit this information to improve
performance?
10. Give an example of an application that could benefit from operating system support for
random access to indexed files.
11. Discuss the merits and demerits of supporting links to files that cross mount points (that
is, the file link refers to a file that is stored in a different volume).

12. Discuss the advantages and disadvantages of associating with remote file systems (stored
on file servers) a different set of failure semantics from that associated with local file
systems.
13. Give an example of a Directory implementation that could benefit from operating
system.

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