Linked allocation in files | Advantages and DIs-advantages

Linked Allocation:
 This method solves the problems associated with contiguous allocation.
 Here the blocks of a single file can be scattered anywhere on the disk.
 The reason because the entire file is implemented as a Linked List.
 Each file is a linked list of disk blocks.
 The directory maintained by the Operating System contains a pointer to the first and the last blocks of a file.
 Each block of a file contains a pointer to the next block after it in the list.
 For creating a new file, we need to just create a new entry in the directory and not to search for sufficient space as in contiguous.

 

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Advantages:
 There's no external fragmentation since each request is for one block.

Disadvantages:

 This method is inefficient for direct files.  It works perfectly for Sequential access only, space needs to be allocated in block for pointers and error in pointer links can lead to Invalid read.

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