How much user-generated data does Google processes each hour?
Google's servers process one quadrillion bytes of user-generated data per hour, or one petabyte. If that sounds like more data than the average army of servers can handle, that's because it is. Google uses literally millions of servers all over the world in order to manage the onslaught of searches that come their way on a daily basis, and this is what's allowed them to become the leader in their field.
SOURCE: Why Is Obama's Top Antitrust Cop Gunning for Google? | Wired