a costumer ask me to sell him netapp storage of 12TB after the installation 10TB was presented to the costumer as usable space. the costumer now Begin to complain that he ask me 12TB and am given him 10TB. Is there a way or a calculator that can generate the raw capacity, usable space of a storage so that one can use it to explain to the costumer before placing order. If there is pleas let me known how i can get it