Magnetic disk drive storage was born in the 1950s — thanks IBM! — but while storage density and power efficiency have rocketed, the lifetime for which data can be stored has remained about the same, at around a decade. That could soon change.
A team of researchers from the University of Twente in the Netherlands has designed and built a disk capable of storing data for, so they claim, over one million years. Perhaps even longer. Wow.
To manage that, they first delved into the theory of how information ages. For data to last, it must be stored in such a way that that one bit of data is distinct from another. Technology Review explains:
This is based on the idea that data must be stored in an energy minimum that is separated from other minima by an energy barrier. So to corrupt data by converting a 0 to a 1, for example, requires enough energy to overcome this barrier... Some straightforward calculations reveal that to last a million years, the required energy barrier is 63 KBT or 70 KBT to last a billion years.
The researchers realised that was very much in the realms of what's possible right now — so they decided to build a disk that would do it. The result is a thin tungsten disk etched with a series of fine lines, coated in protective layer of silicon nitride.
Then came the fun bit: they heated the disks at various temperatures to see how much abuse the data could take. Turns out that, according to Arrhenius law, a disk capable of surviving a million years would have to survive one hour at 445 Kelvin. The researchers' disk survived that with ease, and even withstood temperatures up to 848 Kelvin, though with some significant data loss at that extreme.
The results suggest that we could easily preserve data for future civilisations, though there are of course caveats. The theory used to make the disk applies to a very specific set of circumstances; it might not, for instance, be able to stand a dramatic event like a meteor strike. But, hey, what would? [arXiv via Technology Review]