How do you figure out the transfer time of a cylinder?
CHS (Cylinder/Head/Sector) geometries really don't apply to modern hard-drives (at least from an end-user standpoint), but for the sake of argument let's assume they do. According to Wikipedia, a cylinder is defined as:
Let's futher assume that by "transfer time of a cylinder", we're interested in the amount of time it will take to read, and transmit, all the data in each block in a given cylinder.
So, our definitions:
Because we only need to move the heads once (by definition, all tracks in the cylinder require the heads in the same position), the time to read the data becomes:
Now, we need to figure out the time to transfer that data. Given a transfer speed of x bytes per second, and a data density of b bytes per cylinder, the time to transfer (including the time to read the data) will be:
Now, to determine an actual transfer time, you'll have to plug in the numbers for x, tseek, and ttrack, which will all be device dependent. Even b is device dependent, since modern hard drives don't report their real physical geometries and actually cram a lot more than 63 sectors onto a track (the number varies with the track position -- more near the edge, fewer near the spindle). We can make some other observations (about exactly how to calculate ttrack, which will vary based on the location of the track on the platter), but for general purposes device dependent will suffice.