Let's put into perspective 1 yottabyte:
All Gmail accounts (~500 million users * 10GB/user = ~5000 PB) + All Facebook photos (~2 billion users * 1GB/user = ~2000 PB) + All of Netflix's videos (1-5 PB) + Library of Congress (10-30 PB) + Wikipedia (0.0005 PB)
= ~7000 PB = 7 Exabytes. = 0.0007% of 1 Yottabyte!!!
1 Yottabyte = 250 billion 4TB hard drives.
A hard drive is about 4" x 1" x 5.75".
The Pentagon is a big building (6,636,360 sqft over 5 floors). If you started stacking hard drives inside the Pentagon it would take about 50 pentagons to hold 250 billion hard drives.
At scale you might be able to make a 4TB hard drive for somewhere between $10 and $100.
1 Yottabyte would be $2.5 trillion - $25 trillion in hard drives. That's a couple USA GDPs.
Okay, I think a yottabyte clearly can't be what they mean because that's just unfathomable.
They also mention a 1 million sqft facility.
In a 1 million sqft you can probably pack about 250 million 3.5" hard drives. If each drive was 4TB you'd end up with 1 million PB, or 1000 EB, or 1 Zettabyte
So by Yottabyte they might (maybe) mean Zettabyte. Only off by a factor of 1,000.
Even still, all of the data of Gmail, Facebook, Netflix, Library of Congress, etc is still probably only ~10% of this data center.
Nuts.