File directory definition 54(2)

1. http://raj-os.blogspot.in/ 1 Definition A directory is a file which contains information about other files in the system

2. http://raj-os.blogspot.in/ 2 Contents of a Directory Entry Directory Information about each file Entry1 Entry2 Entry3 Entry4 File name File type File size Owner Protection information Usage count Creation time Time of last modification List of disk blocks used Fig : A directory having an entry for each file

3. http://raj-os.blogspot.in/ 3 File System Organization File systems on a computer system need organization Organization done in two parts 1. Partition file system 2. Create directory

4. http://raj-os.blogspot.in/ 4 Minidisks and Volumes Partitions are known as Minidisks in IBM world Volumes in PC and Macinthosh arenas

5. http://raj-os.blogspot.in/ 5 1 . Partition file system Each disk on a system contains at least one partition A partition is a low level structure Each partition contains files and directories A single disk can have multiple partitions Each partition is treated as a separate storage device i..e. each partition is a virtual disk Some systems group different physical disks into a single partition File System Organization

6. http://raj-os.blogspot.in/ 6 2. Create directory Each partition contains a directory A directory is also known as a device directory or volume table of contents ( VTOC ) The directory records information about all files on that partition File System Organization

7. http://raj-os.blogspot.in/ 7 directory files directory files Partition A Partition B Disk 1 Fig : File system organization – Single disk – Multiple partitions File System Organization

8. http://raj-os.blogspot.in/ 8 Directory Files Partition C Disk 2 Disk 3 Fig : File System organization – Single Partition – Multiple Disks File System Organization

9. http://raj-os.blogspot.in/ 9 Quiz

10. http://raj-os.blogspot.in/ 10 In sequential access method Records are accessed randomly Every alternate record is accessed Records are accessed one after the other None of the above

11. http://raj-os.blogspot.in/ 11 2. Direct access is suitable for a) Payroll application b) Compilation of a source program file c) Airline reservation d) All of the above

12. http://raj-os.blogspot.in/ 12 3. An index file a) Increases speed of accessing data b) Decreases speed of accessing data c) Occupies space in addition to data file d) Both a & c

13. http://raj-os.blogspot.in/ 13 4. The access method to be used for processing student results a) Direct access b) Indexed access c) Sequential Access d) None of the above

14. http://raj-os.blogspot.in/ 14 5. A directory is a) A file b) A storage device c) A system program d) None of the above

15. http://raj-os.blogspot.in/ 15 6. Each entry in a directory stores information such as a) Name of the file b) Size of the file c) Location of the file d) All of the above

16. http://raj-os.blogspot.in/ 16 7. Which of the following is not a directory operation a) Deleting a file b) Creating a file c) Rename a file d) None

17. http://raj-os.blogspot.in/ 17 8. The most common backup device is a) Keyboard b) Printer c) Magnetic tape d) All of the above