Zettabyte

'Everyone in US under virtual surveillance' - NSA whistleblower
Excerpt:

... they [the NSA] are collecting a lot more now and need more storage for it. That facility by my calculations that I submitted to the court for the electronic frontiers foundation against NSA would hold on the order of 5 zettabytes of data. Just that current storage capacity is being advertised on the web that you can buy. And that’s not talking about what they have in the near future.

Comment: See How Much Information is in the World (which has a nice graphic) and Wiki