SCAN Algorithm

SCAN algorithm:

This algorithm is also called the elevator algorithm because of it's behavior. Here, first the head moves in a direction (say backward) and covers all the requests in the path. Then it moves in the opposite direction and covers the remaining requests in the path. This behavior is similar to that of an elevator. Let's take the previous example,

98, 183, 37, 122, 14, 124, 65, 67

Assume the head is initially at cylinder 56. The head moves in backward direction and accesses 37 and 14. Then it goes in the opposite direction and accesses the cylinders as they come in the path.

SCAN algorithm