OS File Allocation Methods

OS File Allocation Methods Visually

Interactive File Allocation Methods with visual animations. Learn contiguous, linked, and indexed allocation with step-by-step visualization and disk block management.

File Allocation Methods Contiguous Allocation Linked Allocation Indexed Allocation Disk Management Memory Mapping Visual Simulation
File System Allocation Control
Used Blocks: 0
Utilization: 0%
Fragmentation: 0%
Disk Blocks (100 blocks) Contiguous Allocation
File Directory
No files allocated

0

Total Files

0%

Disk Utilization

0%

Fragmentation

100%

Access Efficiency

Select allocation method and create files to see disk allocation

File Allocation Methods

File allocation methods determine how files are stored on disk and how the file system keeps track of which blocks belong to which files.

  • Contiguous: Files stored in consecutive blocks
  • Linked: Files stored as linked list of blocks
  • Indexed: Files use index blocks to track data blocks

Contiguous Allocation

Files are allocated in consecutive disk blocks. The directory entry contains the starting block and file length.

Advantages
  • Fast sequential access
  • Simple implementation
  • Minimal seek time
  • Good for read-only files
Disadvantages
  • External fragmentation
  • File size must be known
  • Difficult to extend files
  • Waste of space

Implementation Details

struct DirectoryEntry { char name[8]; int start_block; int length; }; int access_block(file, i) { return file.start_block + i; }

Performance Comparison

Method Sequential Random Space
Contiguous Excellent Good Poor
Linked Good Poor Good
Indexed Fair Good Fair

Key Concepts

  • Fragmentation: Wasted space due to allocation method
  • Locality: Keeping related blocks close together
  • Overhead: Extra space needed for metadata
  • Scalability: Performance with large files/disks

How to Use

  1. Select an allocation method from dropdown
  2. Enter file name and size
  3. Click Allocate to create files
  4. Use Delete to remove files
  5. Try Defrag to reduce fragmentation
  6. Click Reset to clear the disk

Watch how different allocation methods affect disk usage and fragmentation!