Consider a disk queue with requests for I/O to blocks on cylinders 98, 183,…

Solution (SSTF computation):

Start at head position 53. At each step pick the request with the smallest distance from the current head position.

1. Move from 53 to 65: distance = 12, cumulative = 12.

2. Move from 65 to 67: distance = 2, cumulative = 14.

3. Move from 67 to 37: distance = 30, cumulative = 44.

4. Move from 37 to 14: distance = 23, cumulative = 67.

5. Move from 14 to 98: distance = 84, cumulative = 151.

6. Move from 98 to 122: distance = 24, cumulative = 175.

7. Move from 122 to 124: distance = 2, cumulative = 177.

8. Move from 124 to 183: distance = 59, cumulative = 236.

Therefore, the total head movement using SSTF starting at 53 is 236.

Service order produced by SSTF: 65, 67, 37, 14, 98, 122, 124, 183.