Chapter 6, Problem 6.24HW

Suppose that a 2 MB file consisting of 512-byte logical blocks is stored on a disk drive with the following characteristics:

Parameter	Value
Rotational rate	15,000 RPM
Seek	4 ms
Average number of sectors/track	1,000
Surfaces	8
Sector size	512 bytes

  For each case below, suppose that a program reads the logical blocks of the file sequentially, one after the other, and that the time to position the head over the first block is T_{avg seek} + T_{avg rotation}.

1. A.    Best case: Estimate the optimal time (in ms) required to read the file over all possible mappings of logical blocks to disk sectors.
2. B.     Random case: Estimate the time (in ms) required to read the file if blocks are mapped randomly to disk sectors.