In a file allocation system, the following allocation schemes are used: A.…
2021
In a file allocation system, the following allocation schemes are used:
A. Contiguous
B. Indexed
C. Linked allocation
Which of the allocation scheme(s) given above will not suffer from external fragmentation? Choose the correct answer from the options given below:
- A.
A only
- B.
B and C only
- C.
A and B only
- D.
C only
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Correct answer: B
Answer: Indexed allocation and linked allocation do not suffer from external fragmentation.
Contiguous allocation: Requires a file to occupy a single contiguous region of disk blocks. This leads to external fragmentation as free space becomes split into small noncontiguous holes that cannot satisfy larger requests.
Linked allocation: Stores file blocks as a linked list of disk blocks scattered across the disk. Because blocks need not be contiguous, external fragmentation does not occur. Trade-offs: pointer overhead and inefficient random access.
Indexed allocation: Uses an index block that contains pointers to all data blocks of a file, allowing noncontiguous placement of blocks and eliminating external fragmentation. Trade-offs: extra space for the index block, but supports direct access.
Therefore, the correct schemes that do not suffer from external fragmentation are indexed allocation and linked allocation.
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