DVD Longevity

The Preservation Reformatting Lab at NARA in St. Louis maintains an off-line archive consisting of several terabytes of high-resolution document scans on DVD-R discs. We captured these images as part of our ongoing digitization projects, PEP and Burned Record Scanning. After public access versions are generated from these images, they get moved from our server hard drives to DVDs, thus freeing up space that is needed for new work.  
While this off-line disc archive is maintained in ideal conditions, it is nonetheless difficult to estimate how long the DVDs will last without data loss / failure.  Given that the oldest platter is now 7 years old, it makes good sense from a preservation standpoint to begin transferring  the entire archive to newer media.
We are investigating a number of better options which exist today that didn’t seven years ago when our lab first started burning  DVDs.  Blu-ray disc is now used for data storage and provides much higher capacity per platter than DVD (25GB vs. 4.7GB). Another product of interest is the M-Disc, a product with a data layer akin to stone that claims to have a limitless lifespan. Lastly, Sony is working on a professional product called Archival Disc, that is expected to be released sometime in 2015. It will provide very high capacity storage and long estimated lifespan. It is described here: