Suppose that a 1 MB file consisting of 512-byte logical blocks is stored on a disk drive with the following characteristics:

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}.

A. Best case: Estimate the optimal time (in ms) required to read the file given the best possible mapping of logical blocks to disk sectors (i.e., sequential).

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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Parameter Rotational rate Tavg seek Average number of sectors/track Surfaces Sector size Value 13,000 RPM 6 ms 5,000 4 512 bytes