IBM in Zurich and Fuji Film in Japan have already built cassette storage mediums that can store 35 terra bytes of information by using magnetic tape coated with barium ferrite . These are only prototypes but the future looks bright. The size of such a cassette is relatively small 10cm x 10cm x 2cm.
Hard drives can’t keep up with our evolving needs so easily. Improving a hard disk’s density is problematic after a certain point because of physical limits. Furthermore, using cassette tapes instead of hard drives will most likely cut down energy use as demonstrated by Clipper Group in 2010 (link to the study http://www.clipper.com/research/TCG2010054.pdf). According to their study disc drives in large arrays use more power than usual because they tend to remain powered-up. This is expected because a hard disk’s platters spin continuously for a period of time even after a user finished reading or writing. Tapes, on the other hand, only require power when they are recorded on or read.