It's about four times as much as an iPod
In other words, 656 gigabytes is 4.1 times the amount of an iPod, and the amount of an iPod is 0.244 times that amount.(a.k.a. Apple iPod) (2010 figures; for iPod classic, sixth generation)
A sixth-generation, iPod classic MP3 player offers a storage capacity of 160 gigabytes (gB). Data is stored in the unit's hard drive, a 5,400 RPM SATA drive, which measures about 30 sq. cm (5 sq. in)
It's about one-fifth as much as Watson
In other words, 656 gigabytes is 0.16 times the amount of Watson, and the amount of Watson is 6.3 times that amount.(data store only)
Watson, the IBM supercomputer famous for competing against humans on the televised trivia game show Jeopardy!, utilizes 4,100 gigabytes of variously-structured data to formulate answers. While "thinking", Watson processes about 500 gigabytes of data per second.
It's about one-tenth as much as a Gap, Inc. Customer Database
In other words, 656 gigabytes is 0.1 times the amount of a Gap, Inc. Customer Database, and the amount of a Gap, Inc. Customer Database is 10 times that amount.(a.k.a. The GAP Companies, a.k.a. Gap) (2012 figures)
The GAP Inc., the corporate parent of GAP store, Old Navy, and Banana Republic, has accumulated over 7,000 gigabytes of data on almost a billion customers. The GAP, Inc remains the largest apparel retailer in the United States and was the largest in the world from the mid-1990s until about 2008.
It's about twelve times as much as Wikipedia
In other words, 656 gigabytes is 12 times the amount of Wikipedia, and the amount of Wikipedia is 0.08 times that amount.(2009 figures) (all languages)
As of 2009, Wikipedia held 53 gigabytes (gB) of publicly written and edited encyclopedia articles on 14.5 million subjects as well as associated commentary and discussion. Wikipedia is among the ten most popular websites on the Internet and the only non-profit entity in that group.
It's about thirteen times as much as a Blu-ray Disc
In other words, 656 gigabytes is 13 times the amount of a Blu-ray Disc, and the amount of a Blu-ray Disc is 0.08 times that amount.(a.k.a. BD) (dual-layer; Blu-ray disc)
A typical Blu-ray disc will hold 50 gigabytes (gB) of data. The increase in capacity versus a standard DVD is possible because of the smaller wavelength of blue light — 405 nanometers instead of 650 nanometers for the red laser light used in a DVD.
It's about one-sixty-fifth as much as The Amazon.com's databases
In other words, 656 gigabytes is 0.015139 times the amount of The Amazon.com's databases, and the amount of The Amazon.com's databases is 66.053 times that amount.(largest databases only; 2005 figures)
Amazon.com maintains information on the millions of items sold on it's e-Commerce website and the websites of its affiliate companies, as well as information on customer orders and browsing history, and excerpts from nearly a quarter-billion books in databases totaling an estimated 44,370.90 gigabytes of data. Amazon.com receives over 615 million visits to its US website each year.
It's about one-one-hundredth as much as The Google Earth database
In other words, 656 gigabytes is 0.0091 times the amount of The Google Earth database, and the amount of The Google Earth database is 110 times that amount.(2006 figures) (raw imagery and indexes storage)
As of 2006, Google was storing 72,200 gigabytes of raw image and index data for its satellite photo and virtual globe application, Google Earth. The application offers high resolution satellite imagery of 60% of the populated areas of the world, according to 2010 estimates.