Humankind has stored more than 295 billion gigabytes (or 295 exabytes) of data since 1986, according to a new report based on research by scientists at the University of Southern California.
The study, published last week in the Science Express journal, stated that "if a single star is a bit of information, there's a galaxy of information for every person in the world. But it is still less than one percent of the information stored in all the DNA molecules of a human being."
The study tracked some 60 analogue and digital technologies from 1986 to 2007, calculating the amount of data stored, communicated and computed. In 2007, 2.9 X 10^20 optimally compressed bytes were stored, almost X 10^21 bytes were communicated and 6.4 x 10^18 instructions per second were run on general purpose computers.
The study includes information from IT research firms, such as IDC.
For example, it cites IDC's estimate that in 2007 "all the empty or usable space on hard drives, tapes, CDs, DVDs, and memory (volatile and nonvolatile) in the market equalled 264 exabytes. However, using their own methodology, the USC scientists said they counted 276 "optimally compressed" exabytes on digital devices, which occupy 363 exabytes of digital hardware.
Before the digital revolution, the report said, the lion's share of information was stored in analog videotapes, such as VHS cassettes and the like. In 1986, along with VHS tapes, vinyl LP records accounted for 14 percent of stored data, audio cassette tapes made up 12 percent and photography accounted for eight percent.
It was not until 2000 that digital storage made a significant contribution, contributing 25 percent to the data storage total in 2000.
Beginning in 1986, the share of paper-based storage mediums began decreasing, from 33 percent that year to .007% in 2007.
In 2007, hard disk drives held 52 percent of all stored data, optical storage devices held 28 percent, and digital tape about 11 percent.
The majority of our technological memory has been in digital format since the early 2000s, with 94 percent of data stored in that format in 2007, the report indicated.