The seek time plus rotational delay in accessing a particular data block on a disk is usually much longer than the data flow period for most disk transfers. Consider a long sequence of accesses to the 3.5-inch disk given as an example in Section 5.9.1, for either Read or Write operations in which the average block being accessed is 8K bytes long.

(a) Assuming that the blocks are randomly located on the disk, estimate the average percentage of the total time occupied by seek operations and rotational delays.

(b) Repeat part

(a) for the situation in which the disk accesses have been arranged so that in 90 percent of the cases, the next access will be to a data block on the same cylinder.