You must define or select at least two of the three storage configuration values: 1. amount of unused storage to configure [percent or gigabyte], 2. volume size, or 3. volume quantity.
After defining at least two of these, click the Calculate button to automatically fill-in the remaining value of three configurable values. If all three choices are filled in, new calculations will overwrite volume size, based on the amount of unused storage to configure and the volume quantity. Enter only integer values into the fields: remove all spaces, decimal points, or other nonnumeric characters.
Reconsider your storage and volume values and recalculate by clicking the Calculate button.