File directory definition 54(2)


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File directory definition 54(2)

  1. 1. Definition• A directory is a file which contains information about other files in the system 1
  2. 2. Contents of a Directory EntryDirectory Information about each file Entry1 File name File type Entry2 File size Owner Entry3 Protection information Usage count Creation time Entry4 Time of last modification List of disk blocks used Fig : A directory having an entry for each file 2
  3. 3. File System Organization• File systems on a computer system need organization• Organization done in two parts 1. Partition file system 2. Create directory 3
  4. 4. Minidisks and VolumesPartitions are known as• Minidisks in IBM world• Volumes in PC and Macinthosh arenas 4
  5. 5. File System Organization1. 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 5
  6. 6. File System Organization2. 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 6
  7. 7. File System Organization directory Partition A files directory Disk 1 Partition B filesFig : File system organization – Single disk – Multiple partitions 7
  8. 8. File System Organization Directory Disk 2Partition C Files Disk 3Fig : File System organization – Single Partition – Multiple Disks 8
  9. 9. Quiz 9
  10. 10. 1. In sequential access method a) Records are accessed randomly b) Every alternate record is accessed c) Records are accessed one after the other d) None of the above 10
  11. 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 11
  12. 12. 3. An index filea) Increases speed of accessing datab) Decreases speed of accessing datac) Occupies space in addition to data filed) Both a & c 12
  13. 13. 4. The access method to be used for processing student resultsa) Direct accessb) Indexed accessc) Sequential Accessd) None of the above 13
  14. 14. 5. A directory is a) A file b) A storage device c) A system program d) None of the above 14
  15. 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 15
  16. 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 16
  17. 17. 8. The most common backup device is a) Keyboard b) Printer c) Magnetic tape d) All of the above 17