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