CS1411 Lab Exercise 12: File Allocation Techniques solution

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To develop a C program to implement the various file allocation techniques.

Algorithm:

1. Get Main memory size and block size as input.
2. Create a Main memory with ‘n’ number of blocks of equal size.
3. Main memory is maintained as Linked List with structure containing block id, Free /
Filename, Link to next Memory block , Link to Next File block (only for Linked
Allocation), File block table( integer array to hold block numbers only for Indexed
Allocation)

4. Get the number of files and their size as input.
5. Calculate the no. of blocks needed for each file.
6. Select the Allocation Algorithm.

– For every algorithm display Directory information and File information.
7. For Contiguous Allocation – For each file do the following

i. Generate a random number between 1 to ‘n’
ii. Check for continuous number of needed file free blocks starting
from that random block no.
iii. If free then allot that file in those continuous blocks and update
the directory structure.

iv. else repeat step 1
v. If no continuous blocks are free then ‘no enough memory error’
vi. The Directory Structure should contain Filename, Starting Block,
length (no. of blocks)

8. For Linked Allocation- For each file do the following

i. Generate a random number between 1 to ‘n’ blocks.
ii. Check that block is free or not.
iii. If free then allot it for file. Repeat step 1 to 3 for the needed number of blocks
for file and create linked list in Main memory using the
field “Link to Next File block”.

iv. Update the Directory entry which contains Filename, Start block
number, Ending Block Number.
v. Display the file blocks starting from start block number in Directory
upto ending block number by traversing the Main memory Linked list
using the field “Link to Next File block”.

20.For Indexed Allocation – For each file do the following
i. Generate a random number between 1 to ‘n’ blocks for index block.
ii. Check if it is free else repeat index block selection
iii. Generate needed number of free blocks in random order for the file and
store those block numbers in index block as array in File block table array.

iv. Display the Directory structure which contains the filename and index
blocknumber. Display the File Details by showing the index block number’s
File Block Table.
SAMPLE INPUT & OUTPUT:
Main Memory size: 500
Size of each block in the disk: 10 KB
Number of files to be allocated: 5
Name of the File1: ****
Size of the file1: ****

FILE ALLOCATION TECHNIQUES
1. Contiguous
2. Linked
3. Indexed
Choose the Allocation scheme: 1
CONTIGUOUS ALLOCATION
Directory
File Name Start length
***** *** ***
***** *** ***



***** *** ***

Choose the Allocation scheme: 2
LINKED ALLOCATION
Directory
File Name Start End
***** *** ***
***** *** ***



***** *** ***

Individual File listing
File name Data-block 1 Data-block j Data-block k Data-block l Data-block final
Choose the Allocation scheme: 3
INDEXED ALLOCATION
Directory
File Name Indexed Block
***** ***
***** ***



***** ***

Display the Index table for all the files in the following manner
File Name Block Indexed
*** Data-block 1
Data-block j
Data-block k
Data-block l
Data-block final