申論題

5. A disk has 10000 cylinders, each with 10 tracks of 512 blocks. A seek takes 1 ms per cylinder moved. If no attempt is made to put the blocks of a file close to each other, two blocks that are logically consecutive (i.e., follow one another in the file) will require an average seek, which takes 6 ms. If, however, the operating system makes an attempt to cluster related blocks, the mean interblock distance can be reduced to 2 cylinders and the seek time reduced to 200 us. Assuming that the rotational latency is 3 ms and the transfer time is 10 us per block, answer the following questions.

(a) How long does it take to read a 200 block randomly placed file?