Question

A hard disk drive spins at 7,200 rpm. It has a average seek time of 5ms. Calculate the
average access time for the disk drive, showing your working

Answer 1

The question is a little too vague, unfortunately. I'll explain why:

Answer 2

I had to assume it was random access, since if you randomly access a part of a disk, it could be anywhere on the circle, so for every time we'd rotate just a little bit, we'd have to rotate a lot to get another location, if you were to do this many many times, you'd find that the average is
1/2 a revolution of a disk.

which is 1/240th of a second. Add that to your seek time to get the total access time.


Sorry if that is long winded. I find the average access time a little tricky to understand. Best of luck to you!