Thanks for the suggestion. As far as I see, it's up to 50 PB raw data per library, and such a library needs 16 frames (frame is what we call a rack, "1,800 mm H × 782 mm W × 1,212 mm D") so it's cca 3 PB (3e15) per rack. With 2.5K racks on site (100K sqft data center space according to Wikipedia) it's still cca 8 exabytes (8e18) in the whole data center.