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    File Systems and Storage Allocation Notes for GATE CS

    File Systems and Storage Allocation notes for GATE CS: 25 study cards covering concepts, formulas, shortcuts and exam traps, plus solved practice questions.

    file systems and storage allocation notes

    Chapter Roadmap: File Systems and Storage Allocation

    Chapter Journey

    File Systems & Storage Allocation

    1. Contiguous & Linked Allocation

    Mapping logical files to physical disk blocks. Trade-offs between linear and chained storage.

    2. Directory Search & Operations

    Locating files, managing metadata, and analyzing search efficiencies.

    3. Free-Space Management

    Tracking available disk blocks using bitmaps and linked lists.

    Why start here? Understanding how individual files are stored is the foundational step before analyzing directories and free space.

    Hero Concept: The File Allocation Problem

    The File Allocation Problem

    How do we map the logical blocks of a file to the physical blocks on a disk?

    Efficient Access
    Minimize disk head movement
    Space Efficiency
    Minimize fragmentation
    Dynamic Growth
    Expand without moving data

    Foundational Strategies

    Contiguous Allocation

    Blocks are stored in adjacent physical sectors.

    Linked Allocation

    Blocks are scattered, but chained together via pointers.

    Contiguous Allocation: The Linear Approach

    Contiguous Allocation

    Each file occupies a set of contiguous (adjacent) blocks. If a file starts at block with length , it occupies .

    Start ()
    End ()
    Dir Entry:
    Start address + Length
    Random Access:
    time ()
    Pros: Extremely fast sequential & random access.
    Cons: External fragmentation. Difficult to grow files.

    22 more cards in this chapter

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    File Systems and Storage Allocation Notes for GATE CS

    File Systems and Storage Allocation notes for GATE CS: 25 study cards covering concepts, formulas, shortcuts and exam traps, plus solved practice questions.

    Chapter Roadmap: File Systems and Storage Allocation

    Chapter Journey

    File Systems & Storage Allocation

    1. Contiguous & Linked Allocation

    Mapping logical files to physical disk blocks. Trade-offs between linear and chained storage.

    2. Directory Search & Operations

    Locating files, managing metadata, and analyzing search efficiencies.

    3. Free-Space Management

    Tracking available disk blocks using bitmaps and linked lists.

    Why start here? Understanding how individual files are stored is the foundational step before analyzing directories and free space.

    Hero Concept: The File Allocation Problem

    The File Allocation Problem

    How do we map the logical blocks of a file to the physical blocks on a disk?

    Efficient Access
    Minimize disk head movement
    Space Efficiency
    Minimize fragmentation
    Dynamic Growth
    Expand without moving data

    Foundational Strategies

    Contiguous Allocation

    Blocks are stored in adjacent physical sectors.

    Linked Allocation

    Blocks are scattered, but chained together via pointers.

    Contiguous Allocation: The Linear Approach

    Contiguous Allocation

    Each file occupies a set of contiguous (adjacent) blocks. If a file starts at block with length , it occupies .

    Start ()
    End ()
    Dir Entry:
    Start address + Length
    Random Access:
    time ()
    Pros: Extremely fast sequential & random access.
    Cons: External fragmentation. Difficult to grow files.

    Linked Allocation: The Chain Approach

    Linked Allocation

    Each file is a linked list of disk blocks. Blocks can be scattered anywhere on the disk.

    Data
    Ptr
    Block 1
    Data
    Ptr
    Block 2
    Data
    NULL
    Block 3
    Dir Entry:
    Start address only
    Random Access:
    traversal
    Pros: No external fragmentation. Easy file growth.
    Cons: Poor random access. Pointer overhead (internal frag).

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