Exercise 13.3.1: Suppose we are scheduling I/O requests for a Megatron 747 disk, and the requests in Fig. 13.9 are made, with the head initially at track 32,000. At what time is each request serviced fully if: a) We use the elevator algorithm (it is permissible to start moving in either direction at first) b) We use first-come-first-served scheduling. 574 CHAPTER 13. SECONDARY STORAGE MANAGEMENT Cylinder First time of Request available 8000 48000 4000 40000 10 20 Figure 13.9: Arrival times for four block-access requests Exercise 13.3.1: Suppose we are scheduling I/O requests for a Megatron 747 disk, and the requests in Fig. 13.9 are made, with the head initially at track 32,000. At what time is each request serviced fully if: a) We use the elevator algorithm (it is permissible to start moving in either direction at first) b) We use first-come-first-served scheduling. 574 CHAPTER 13. SECONDARY STORAGE MANAGEMENT Cylinder First time of Request available 8000 48000 4000 40000 10 20 Figure 13.9: Arrival times for four block-access requests