Consider a disk queue with requests for I/O to blocks on cylinders 47, 38,…

Key idea: Use the C-LOOK algorithm: service requests in increasing cylinder order while moving towards larger cylinder numbers, then jump to the smallest pending request and continue in increasing order.

Initial head position: 63. Request cylinders: 47, 38, 121, 191, 87, 11, 92, 10.

Requests greater than 63 (serve first, in increasing order): 87, 92, 121, 191.

Requests less than or equal to 63 (served after the wrap, in increasing order): 10, 11, 38, 47.

• Move from 63 to 87: 24

• Move from 87 to 92: 5

• Move from 92 to 121: 29

• Move from 121 to 191: 70

• Wrap (jump) from 191 to 10: 181

• Move from 10 to 11: 1

• Move from 11 to 38: 27

• Move from 38 to 47: 9

Sum of movements: 24 + 5 + 29 + 70 + 181 + 1 + 27 + 9 = 346 cylinders.