Henry Newman and I talk about quite a few things, and one of my favorite articles he has ever written is this one, called, "Rocks Don't Need to Be Backed Up." In the article, he talks about how current electronic data storage has some potential problems if you want to keep the data for a long time. The definition of a "long time" is in the eyes of the beholder I think, but when you have the National Science Foundation (NSF) asking that the data from funded projects be available for 20 years, then you have an idea of the time frame. An even better example is the LDS church that has massive amounts of genealogical data that they want to make available electronically, but they want to keep those records for hundreds of years.
How do we effectively storage electronic data for long periods of time? As Henry pointed out in this article, have you tried to read a file from 20 years ago that you haven't actively used? How do you make sure that the data has not been corrupted? How do you access the data if the interfaces have changed? Lots of questions surround data preservation, particularly when its electronic.
A recent startup, Millenniata and Hitachi-LG Data Systems announced a new optical disk and a read/write player that they are saying can store data forever (not sure how you test forever, but that's another story). Both companies are saying that the data can be accessed using any current DVD or Blu-Ray player. Furthermore, the company claims that the product, called the M-Disc, can be dipped into liquid nitrogen and then dropped into boiling water without harming it (i.e., the data is intact and can be accessed). It is so resilient that the CEO of Millenniata, Scott Shumway, calls the substance in the disk, "stone-like." I think this fulfills Henry's "rocks" definition.
Be sure to take a look a this technology. If it pans out, it could be the wave of the future for archiving data.