File allocation methods (contiguous, linked, indexed) in Operating Systems - Interactive Code Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to identify the file allocation method that stores files in consecutive blocks.

Operating Systems

method = "[1]"  # This method stores files in consecutive blocks on disk.

Drag options to blanks, or click blank then click option'

Acontiguous

Blinked

Cindexed

Dhashed

Attempts:

3 left

💡 Hint

Common Mistakes

Confusing linked allocation with contiguous because both deal with blocks.

Choosing indexed because it uses a separate index block.

The contiguous allocation method stores all blocks of a file in consecutive order on the disk, making access fast and simple.

2fill in blank

medium

Complete the code to name the file allocation method that uses pointers to link file blocks.

Operating Systems

method = "[1]"  # This method stores file blocks linked by pointers.

Drag options to blanks, or click blank then click option'

Aindexed

Bcontiguous

Clinked

Dsequential

Attempts:

3 left

💡 Hint

Common Mistakes

Choosing contiguous because it also deals with blocks.

Confusing indexed allocation with linked.

The linked allocation method stores each file block with a pointer to the next block, forming a chain.

3fill in blank

hard

Fix the error in the code to correctly identify the file allocation method that uses an index block.

Operating Systems

method = "[1]"  # This method uses an index block to store all block addresses.

Drag options to blanks, or click blank then click option'

Acontiguous

Bindexed

Cdirect

Dlinked

Attempts:

3 left

💡 Hint

Common Mistakes

Choosing linked because it also uses pointers.

Choosing contiguous because it stores blocks together.

The indexed allocation method uses a special index block that contains pointers to all the file's blocks, allowing direct access.

4fill in blank

hard

Fill both blanks to complete the description of the linked allocation method.

Operating Systems

In linked allocation, each file block contains [1] to the next block, and there is no need for [2] storage.

Drag options to blanks, or click blank then click option'

Aa pointer

Bcontiguous

Cextra index

Dsequential

Attempts:

3 left

💡 Hint

Common Mistakes

Choosing 'contiguous' for the second blank, which is unrelated to index storage.

Confusing pointer with sequential.

Linked allocation stores a pointer in each block to the next block, so it does not require extra index storage like indexed allocation.

5fill in blank

hard

Fill all three blanks to complete the dictionary that maps allocation method names to their descriptions.

Operating Systems

file_methods = {"contiguous": "Stores files in [1] blocks", "linked": "Uses [2] to link blocks", "indexed": "Uses an [3] block"}

Drag options to blanks, or click blank then click option'

Aconsecutive

Bpointers

Cindex

Drandom

Attempts:

3 left

💡 Hint

Common Mistakes

Mixing up 'index' and 'pointer' terms.

Choosing 'random' which is unrelated.

The dictionary describes each method: contiguous uses consecutive blocks, linked uses pointers, and indexed uses an index block.

Practice

1. Which file allocation method stores all file blocks in one continuous sequence on disk?

easy

A. Hybrid allocation

B. Linked allocation

C. Indexed allocation

D. Contiguous allocation

Solution

1. Step 1: Understand file storage methods

   Contiguous allocation stores all file blocks one after another in a continuous space on disk.

2. Step 2: Compare with other methods

   Linked allocation stores blocks scattered with pointers; indexed uses an index block. Only contiguous is continuous.

3. Final Answer:

   Contiguous allocation -> Option D

4. Quick Check:

   Continuous blocks = Contiguous allocation [OK]

Hint: Continuous blocks mean contiguous allocation [OK]

Common Mistakes:

• Confusing linked allocation with contiguous
• Thinking indexed allocation stores blocks continuously
• Assuming hybrid is a standard method

2. Which of the following is the correct way to describe linked allocation?

easy

A. File blocks are stored in a continuous sequence

B. Each file block contains a pointer to the next block

C. An index block contains pointers to all file blocks

D. File blocks are stored in a fixed-size table

Solution

1. Step 1: Recall linked allocation structure

   In linked allocation, each file block stores a pointer to the next block, forming a chain.

2. Step 2: Eliminate other options

   Continuous sequence is contiguous; index block is indexed allocation; fixed-size table is unrelated.

3. Final Answer:

   Each file block contains a pointer to the next block -> Option B

4. Quick Check:

   Pointers in blocks = Linked allocation [OK]

Hint: Pointers inside blocks mean linked allocation [OK]

Common Mistakes:

• Mixing up index block with linked pointers
• Thinking linked allocation stores blocks continuously
• Confusing fixed-size table with file allocation

3. Consider a file stored using indexed allocation with an index block containing pointers to data blocks 5, 9, and 12. Which block does the system read first to access the file?

medium

A. The index block

B. Block 5

C. Block 9

D. Block 12

Solution

1. Step 1: Understand indexed allocation access

   The system first reads the index block to find pointers to all data blocks.

2. Step 2: Identify the first block read

   Before accessing data blocks 5, 9, or 12, the index block must be read to know their locations.

3. Final Answer:

   The index block -> Option A

4. Quick Check:

   Index block read first in indexed allocation [OK]

Hint: Index block is always read first in indexed allocation [OK]

Common Mistakes:

• Choosing a data block instead of the index block
• Confusing linked allocation with indexed
• Assuming direct access without index

4. A file system uses linked allocation but the file's blocks are stored non-contiguously without pointers linking them. What is the main problem here?

medium

A. File blocks are stored contiguously, causing slow access

B. File blocks are fragmented but linked correctly

C. Pointers are missing, so file blocks cannot be accessed sequentially

D. Index block is corrupted

Solution

1. Step 1: Understand linked allocation requirements

   Linked allocation requires each block to have a pointer to the next block for sequential access.

2. Step 2: Identify the problem without pointers

   Without pointers, the system cannot follow the chain, so blocks cannot be accessed in order.

3. Final Answer:

   Pointers are missing, so file blocks cannot be accessed sequentially -> Option C

4. Quick Check:

   Missing pointers break linked allocation chain [OK]

Hint: No pointers means linked allocation fails [OK]

Common Mistakes:

• Assuming fragmentation is not a problem
• Confusing contiguous storage with linked allocation
• Thinking index block is involved in linked allocation

5. A file of size 12 blocks is stored using contiguous allocation starting at block 20. If block 25 is corrupted, what is the impact on the file access?

hard

A. The entire file becomes inaccessible due to break in continuity

B. File access continues using pointers from block 25

C. Only block 25 is lost; other blocks are accessible

D. Index block redirects access around block 25

Solution

1. Step 1: Recall contiguous allocation properties

   Files are stored in continuous blocks; any corruption breaks the sequence.

2. Step 2: Analyze impact of corrupted block 25

   Since block 25 is in the middle, the file cannot be read beyond that point, making the entire file inaccessible.

3. Final Answer:

   The entire file becomes inaccessible due to break in continuity -> Option A

4. Quick Check:

   Corruption breaks contiguous file access [OK]

Hint: Contiguous files fail if any block is corrupted [OK]

Common Mistakes:

• Assuming only corrupted block is lost
• Thinking pointers or index block help in contiguous allocation
• Confusing linked or indexed allocation behavior