The document discusses different disk scheduling disciplines:
- FCFS handles requests in the order they arrive but may have long seek times.
- SSTF selects the closest request to reduce seeks but can result in starvation.
- SCAN adopts an elevator algorithm but a new request could wait for almost two full scans in a heavily loaded disk.
- C-SCAN always scans in one direction and returns to track 0 between scans.
- LOOK is similar to SCAN but uses request information to change the head direction when no requests are beyond the current point.
