Which part of storage cost do we want to calculate?

In order to calculate the storage capacity we need the following information:

$ The cost of storing the information carrier. In other words: the cost of storing the carriers in a unit space divided by the number of carriers. One can call this the hard storage volume.

The product of an archive is the quantity of information that it holds. It is more correct to calculate the actual cost of the archive product:

$ The cost of storing the information. In other words: the cost of storing the information on the carriers in a unit space divided by the hours of information stored. This could be expressed as soft volume.

This is a handy starting point for calculation purposes.