If you believe the information found on DVD packaging, you shouldn’t have any concerns about placing your wedding video, important business documents, family archive photos, etc. on DVDs that use gold as their reflective layer or are a little more expensive and sold under the label, “archive DVD” (a bit of an oxymoron really… keep reading). You wouldn’t have any concerns about using such DVDs for long-term storage since their packages are emblazoned with claims of ten, twenty, fifty and even one-hundred -year life expectancy. You’d sleep well knowing your fondest, most important memories and information are securely preserved.

So why are people who make a living from storing crucial, one-of-a-kind digital data not following your lead? What’s keeping librarians, archivists, photographers and genealogists from running down the same path for their long-term storage needs? The best answer may be found in a presentation prepared by the Memory of the World Programme’s Sub-Committee on Technology. This provides detailed guidance on assessing the risks associated with storing archival data on recordable CDs and DVDs.

Here are some of the warnings from the document that consumers will be well-advised to heed as they run contrary to what manufacturers and marketers of recordable DVDs have been telling us:

1. (Preface) Around [the year] 2000 … Concerns about the reliability of recordable CDs and DVDs were also supported by an increasing number of reports of discs failing at the time of their production.
2. (Preface) … and while several products have been marketed since which attempt to optimise their longevity, the principle problem remained unsolved.
3. (Introduction) Even though subsequent technological development has improved on many of the early manufacturing faults no credible claim can be made to permanence.
4. (Introduction) Recordable CDs and DVDs are often chosen as archival carriers, however, the risk of failure of a storage system based on this type technology is high when compared to other approaches.
5. (Page 10) Error measurement is a critical part of producing reliable data on a recordable disc. The fact that the data is able to be read, as assessed by “verification”, is not sufficient indication on its own because a disc with a high level of errors can sometimes still be read, but is very likely to fail soon after.
6. (Page 10) Dye type, though significant, is only one of the factors determining the life of the media. The variation in the amount of dye used in the dye layer, a result of the manufacturers’ race for even higher recording speeds and higher density recording, is a contributing factor in the long term failure of recordable optical media.
7. (Page 10 ) It should be noted that discs optimised for high speed recording use less dye, which may indicate a shorter life expectancy. DVD-R uses less dye as a matter of course, as the data rate when writing to a recordable DVD is much higher than for CD-R.
8. (Page 11) Many discs that appear to be reputable brands may turn out to have been manufactured by a second party and repackaged for sale.
9. (Page 13) The error correction capability of most replay equipment will mask the effects of degradation until the errors are well into the uncorrectable region. When this point is reached, all subsequent copies are irreversibly flawed.
10. (Page 15) The use of recordable and rewritable CD/DVDs as archival carriers cannot be advocated unless a strict testing and monitoring program is set up. It should be noted that testing and analysing, though absolutely necessary, will be time consuming, adding long-term costs to the archival solution. When planning an archival strategy, these costs should be included.
11. (Conclusion) Recordable CDs and more recently DVDs are very popular storage media. Because of the relative simplicity of their production, their easy availability and their financial affordability they have been very frequently used in projects to preserve and make accessible cultural and scientific documents of all kinds. As they were never intended for use as reliable media for long term preservation and have been developed primarily as a consumer product for the mass market their use in critical archival and preservation contexts constitutes a significant risk.

This document was revisited by the Sub-Committee in 2008 and found to continue to be relevant and useful.