LOOK disk scheduling is similar to the SCAN disk scheduling algorithm except for the difference that the disk arm in spite of going to the end of the disk goes only to the last request to be serviced in front of the head and then reverses its direction from there only. Thus, it prevents the extra delay which occurred due to unnecessary traversal to the end of the disk.

Characteristics of LOOK :

The disk arm goes directly to last request to be serviced & then reverses its direction from there only.

Advantages of LOOK :

It does not cause the head to move till the ends of the disk when there are no requests to be serviced.
It provides better performance as compared to SCAN Algorithm.
It does not lead to starvation.
provides low variance in response time and waiting time.

Disadvantages of SCAN :

There is an overhead of finding the end requests.
It causes long waiting time for the cylinders just visited by the head