Contiguous allocation in Operating Systems - Practice Problems & Coding Challenges

Challenge - 5 Problems

🧠 Conceptual

intermediate

Understanding Contiguous Allocation

Which of the following best describes contiguous allocation in file storage?

A Files are stored in scattered blocks linked by pointers, reducing fragmentation but slowing access.

B Files are stored in consecutive blocks on the disk, making access faster but causing external fragmentation.

C Files are divided into fixed-size blocks stored anywhere on the disk with an index table.

D Files are stored in a hierarchical directory structure without concern for physical location.

💡 Hint

Think about how files are placed physically on the disk and the impact on speed and fragmentation.

Contiguous allocation stores files in consecutive disk blocks, which allows fast access but can cause external fragmentation as free space gets divided into small chunks.

📋 Factual

intermediate

Fragmentation in Contiguous Allocation

What type of fragmentation is most commonly associated with contiguous allocation?

A Internal fragmentation due to fixed block sizes.

B Fragmentation caused by file system journaling.

C No fragmentation occurs in contiguous allocation.

D External fragmentation caused by scattered free spaces.

💡 Hint

Consider how free space is divided when files are stored in consecutive blocks.

External fragmentation happens because free space is broken into small pieces that may not be large enough for new files, a common issue in contiguous allocation.

🚀 Application

advanced

Calculating Free Space for Contiguous Allocation

A disk has 1000 blocks. Files A, B, and C occupy 200, 300, and 100 contiguous blocks respectively. If the free space is fragmented into three parts of 150, 100, and 150 blocks scattered across the disk, what is the largest file size that can be stored contiguously?

A 400 blocks

B 300 blocks

C 150 blocks

D 450 blocks

💡 Hint

Look for the largest single free space chunk available for contiguous storage.

The largest contiguous free space chunk is 150 blocks, so the largest file that can be stored contiguously must fit within that size.

🔍 Analysis

advanced

Comparing Contiguous Allocation with Other Methods

Which of the following is a key disadvantage of contiguous allocation compared to linked allocation?

A It suffers from external fragmentation and requires compaction.

B It requires more disk space for pointers.

C It cannot support random access to file blocks.

D It causes slower sequential access to files.

💡 Hint

Think about how files are stored and the impact on free space management.

Contiguous allocation causes external fragmentation because files must occupy consecutive blocks, often requiring disk compaction to reclaim space.

❓ Reasoning

expert

Effect of File Size Changes in Contiguous Allocation

If a file stored using contiguous allocation needs to grow beyond its allocated space, what is the most likely consequence?

A The file must be moved to a larger contiguous free space, causing overhead.

B The file can automatically extend into the next free block without moving.

C The file system will split the file into linked blocks to accommodate growth.

D The file size cannot be changed once allocated.

💡 Hint

Consider the requirement for contiguous blocks and what happens if the next blocks are occupied.

Since contiguous allocation requires consecutive blocks, if the file grows beyond its space, it must be relocated to a larger free contiguous area, which is costly.