According to the computer industry, the amount of data stored on IT systems is doubling roughly every 18 months to two years. Industry watchers believe that the total size of the worldwide digital archive stands at just short of 10m petabytes.

Much of that data is being generated by businesses, in the form of e-mails, PowerPoint presentations and the output from enterprise IT systems. Another large chunk of data comes from the move towards digital storage and distribution of music, TV, photographs and even books.