Magnetic tape has been used as a storage medium continuously from one of the first contemporary computers onwards -- the UNIVAC, in 1951. That gives it 60 years of unbroken use, from gigantic reel-to-reel rolls of the stuff to tape cartridges that might one day hold 70 terabytes apiece.
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http://www.technologyreview.com/blog/mimssbits/26990/