How do I compute the capacity of a hard disk?
I have a worked example of how to compute the capacity of a hard disk, could anyone explain where the BOLD figures came out of?
RPM: 7200
no of sectors: 400
no of platters: 6
no of heads: 12
cylinders: 17000
avg seek time: 10millisecs
time to move between adj cylinders: 1millisec
the first line of the answer given to me is:
12 x 17 x 4 x 512 x 10^5
I just want to know where the parts in bold came from.The 512 I dont know. The 10 is from the seek time but its power 5?
Answer
The answer is
heads x cylinder x sectors x 512 (typical size of one sector in bytes)
so this is
12 x 17000 x 400 x 512
which is the same as
12 x 17 x 1000 x 4 x 100 x 512
and
100 = 10^2
1000 = 10^3
10^2 x 10^3 = 10^5
As you want the capacity, you don't need any times here.
A reference for the 512 bytes can be found at Wikipedia, for example (and it also has a similar example with the same formula a bit below).