C-SCAN Scheduling

• Circular SCAN (C-SCAN) scheduling is a variant of SCAN designed to provide a more uniform wait time.
• Like SCAN, CSCAN moves the head from one end of the disk to the other, servicing requests along the way.
• When the head reaches the other end, however, it immediately returns to the beginning of the disk, without servicing any requests on the return trip (see Fig. 11).

  Figure 11: C-SCAN disk scheduling.