What is Linked Allocation?
- In this scheme, each file is a linked of disk blocks which need not be The disk blocks can be scattered anywhere on the disk.
- Each block contains a pointer to the next block occupied by the file.
Example: The file ‘jeep’ in following image shows how the blocks are randomly distributed. The last block (25) contains -1 indicating a null pointer and does not point to any other block.
Advantages of Linked Allocation
This is very flexible in terms of file size. File size can be increased easily since the system does not have to look for a contiguous chunk of memory.
- This method does not suffer from external fragmentation. This makes it relatively better in terms of memory utilization.
Disadvantages Linked Allocation:
- Because the file blocks are distributed randomly on the disk, a large number of seeks are needed to access every block individually. This makes linked allocation slower.
It does not support random or direct access. We can not directly access the blocks of a file. A block k of a file can be accessed by traversing k blocks sequentially (sequential access ) from the starting block of the file via block pointers.
