Yottabyte

In March 2012 Wired published a story about NSA's Bluffdale Utah $2 billion Data Centre which occupies a million square feet:
The NSA Is Building the Country’s Biggest Spy Center (Watch What You Say)

In the article it claimed "the potential amount of information that could be housed in Bluffdale is truly staggering. But so is the exponential growth in the amount of intelligence data being produced every day by the eavesdropping sensors of the NSA and other intelligence agencies. As a result of this “expanding array of theater airborne and other sensor networks,” as a 2007 Department of Defense report puts it, the Pentagon is attempting to expand its worldwide communications network, known as the Global Information Grid, to handle yottabytes (10²⁴ bytes) of data."

How much is a Yettabyte?
1 YB = 1000000000000000000000000bytes = 1000⁸bytes = 
             10²⁴bytes = 1000zettabytes = 1 trillion terabytes.



http://gizmodo.com/5557676/how-much-money-would-a-yottabyte-hard-drive-cost



Update -  NSA's Bluffdale to hold 5 Zettabytes of Storage:
http://foxnewsinsider.com/2013/06/07/how-much-zettabyte-nsa-utah-facility-can-hold-immense-amount-data