Difference Between Internal and External Fragmentation

Difference Between Internal and External Fragmentation in Tabular Form

  • Fragmentation is of two types
  1. Internal fragmentation.
  2. External fragmentation.
  • In fragmentation, OS cannot use a certain area of available memory.
  • The Basic Difference Between Internal and External Fragmentation is that Internal fragmentation Means that the file uses more disk space than the declared size because the amount of disk used must be multiples of the size of given record size. External Fragmentation means Total Memory space exists to satisfy a request, but it is not contiguous.

Comparison Chart

Internal fragmentationExternal fragmentation
Memory allocated to a process may be slightly larger than the requested memory. The difference between these two numbers is internal fragmentation.External fragmentation exists when there is enough total memory space to satisfy a request but available spaces are not contiguous.
First-fit and best-fit memory allocation do not suffer from internal fragmentation.First-fit and best-fit memory allocation suffer from external fragmentation.
Systems with fixed-sized allocation units, such as the single partitions scheme and paging suffer from internal fragmentation.Systems with variable-sized allocation units, such as the multiple partitions scheme and segmentation suffer from external fragmentation.

Internal fragmentation

  • There is wasted space internal to a partition due to the fact that the block of data loaded is smaller than the partition is called internal fragmentation.
  • Image show an internal fragmentation.
  • To keep track of this free hole is overhead for system.
Internal fragmentation
Internal fragmentation

 External fragmentation

  • It occurs when enough total main memory space exists to satisfy a request, but it is not contiguous, storage is fragmented into a large number of small holes.
  • Image shows external fragmentation.
  • Following are the solution for external fragmentation
    2. Logical address space cf a process/program
External fragmentation

Related Differences:

    1. Difference Between Monolithic Kernel and Microkernel in Tabular Form
    2. Difference Between Contiguous and Noncontiguous Memory Allocation


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