Contiguous allocation requires that each file occupy a set of contiguous blocks on the disk.assuming that only one job is accessing the disk accessing block b+1 after block b normally requires no head movement. when head movemrnt is needed the head need only move from one track to the next.
Linked allocation solves all problems of contiguous allocation. with linked allocation, each file is a linked list of disk blocks the disk block may be scattered anywhere on the disk.
Indexed allocation sol