I recently posted some information about the short life expectancy of digital media. Since then, I have run across another source that provides some excellent insight into the fragile existence of recordable compact discs (CD-Rs) and recordable digital versatile/video discs (DVD±Rs).
The Canadian Conservation Institute publication Longevity of Recordable CDs and DVDs provides authoritative information. Explained are the various factors that influence how long a disc lasts, which include disc quality, recording methods, handling and storage.
I found especially useful a listing of “the relative stability of optical disc formats.” Formats are listed from most to least stable:
- CD-R (phthalocyanine dye, gold metal layer)
- CD-R (phthalocyanine dye, silver alloy metal layer)
- DVD-R (gold metal layer)
- CD (read-only, e.g. audio CD)
- DVD (read-only, e.g. movie DVD)
- DVD-R (silver alloy metal layer)
- CD-R (azo dye, silver alloy metal layer)
- CD-R (cyanine dye, silver alloy metal layer)
It is sobering to realize how many ways that optical discs can give up the ghost. Unfortunately, other digital storage media also have their shortcomings in terms of longevity. The best advice is still to have multiple copies of important data stored on different kinds of media.