CSE 120 -- Homework #4

Out: 11/21/00
In: 11/30/00

1. Chapter 15, Section 15.12: A refinement of 15.21: Suppose that a disk has 200 cylinders numbered 0 to 199, and the head is at cylinder 0. The disk has a queue of pending requests in the following FIFO order:

   45, 132, 30, 23, 198, 170, 180, 78, 73, 150

   Starting from the current head position, what is the total distance in cylinders that the disk arm moves to satisfy all of the requests for each of the following disk-scheduling algorithms?
   • FCFS
   • SSTF
   • Elevator

2. [Silberschatz] What are the advantages and disadvantages of recording the name of the program that creates a file with the file's attributes (as is done in the Macintosh operating system)?

3. Chapter 17, Section 17.13: 17.9, 17.12.

4. [Silberschatz] Consider a file system that supports the strategies of contiguous, linked, and indexed allocation. What criteria should be used in deciding which strategy is best utilized for a particular file?