LOOK
o Like SCAN except stops moving inwards (or outwards) when no more requests in that direction exist.
C-SCAN (circular scan)
o Moves inwards servicing requests until it arrive at the innermost cylinder then jumps to the outside cylinder of the disk without servicing any requests.
o Replicate this over and over.
o Variant service needs from inside to outside and then skip back to the innermost cylinder.
C-LOOK
o Moves inwards servicing needs until there are no more requests in that direction and then it jumps to the outermost outstanding requests.
o Replicate this over and over.
o Variant service requirements from inside to outside after that skip back to the innermost request.