Not only is tape back-up still around, but it’s also still beating disk

The classic strength of tape compared to disk is in the relative cheapness, but now there’s more. If you’re thinking in terms of long-term archives, then tape also beats disk, because it has a “shelf life” of 30 years, compared to a “measly” 10 years for disk. After 10 years, disk runs the risk of “bit rot”, and data that then become corrupted. Tape also has yet more up its sleeve. Storage volumes are set to increase without limit for tape, whereas for hard disks, some of the physical limits are becoming all too apparent.

The challenge for disks is in what is known as the “areal density”, meaning how much data you can pack into a square inch. Disks suffer from the problem that the more a given area is loaded with data, the more the magnetic particles in that area become unstable or unreliable. Tape on the other hand has more headroom and is still growing in terms of data capacity. New magnetic media for tapes are more stable than ever. New tape storage architectures are easing the inflexibility of sequential storage that had always been a drawback for tape compared to the random access possible via disk.

As in indication of the storage potential of tape compared to disk, storing 32 terabytes of data on a tape cartridge is already a reality: IBM recently (end of 2012) announced 35 terabyte data tape products. Other statistics show cost advantages in that tape is 15 times less expensive to acquire and use (total cost of ownership), compared to disk. Tape also requires less than 0.5% of the energy that would otherwise be needed to archive data to disk. All in all, tape is set to give disk storage a run for its money for some time to come.