Kleeck: It won't require 190 racks... 10.488TH solution won't use 2Full racks. The question is can you make efficient use of the space.

Ken: I'd suggest you consider 1 Head + 9 Expansion per rack and keep it to a system per rack. This would be easier to manage. It would give you 140 cards per rack or 6.3TH.

Or roughly 160 racks.