Today's file systems include a number of techniques for improving disk I/Os. In particular, three major points for efficient I/Os are (1) how to exploit the speed difference between the main memory and hard disks, (2) how to manage the head motion of hard disk, and (3) how to organize data placement on hard disks. Describe the three kinds of techniques used in modern file systems. Include in your answer quantitative description of the techniques.
See [PAT97] for a detailed answer.