Estimated Capacity is used to calculate the percent full number when a tape
has not filled up yet, that is it.  So you want to use a number that kind of
represents what you are getting on a tape if you like to look at a percent
full number.  Otherwise, it is kind of useless.  When the tape actually
fills up the real capacity bytes will show.

For 3590 users or 3490E users with various length tapes there is not a good
way to segregate the capacities so we just put in 100GB for 3590 tapes.