C-LOOK Algorithm
As LOOK is similar to SCAN algorithm, in a similar way, CLOOK is similar to CSCAN disk scheduling algorithm. In CLOOK, the disk arm in spite of going to the end goes only to the last request to be serviced in front of the head and then from there goes to the other end’s last request. Thus, it also prevents the extra delay which occurred due to unnecessary traversal to the end of the disk.
In this algorithm, the head services requests only in one direction(either left or right) until all the requests in this direction are not serviced and then jumps back to the farthest request on the other direction and service the remaining requests which gives a better uniform servicing as well as avoids wasting seek time for going till the end of the disk.
Example Input: Request sequence = {176, 79, 34, 60, 92, 11, 41, 114} Initial head position = 50 Direction = right (Moving from left to right) Output: Initial position of head: 50 Total number of seek operations = 156 Seek Sequence is 60 79 92 114 176 11 34 41
The following chart shows the sequence in which requested tracks are serviced using C-LOOK.
Therefore, the total seek count = (60 – 50) + (79 – 60) + (92 – 79) + (114 – 92) + (176 – 114) + (176 – 11) + (34 – 11) + (41 – 34) = 321