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M-DISC: Long-Term Optical Storage?

Recently I heard about the storage technology known as M-DISC, a write-once optical format that claims to last against extreme temperatures and oxidization, providing safe storage of data for up to 1,000 years. This sounds good, but is any of it true?

M-DISC logo

What is M-DISC?

Developer Millenniata claims that M-DISC uses a "glassy carbon" data layer which is sort of like chiseling your data into stone. (Of course, even stone tablets aren't immune to data rot.) M-DISCs are expensive, going for around $3 US each for the 4.7GB DVD discs, and they aren't compatible with all players. As with other Blu-Ray formats, M-DISCs are available in 25, 50, and 100GB versions as well.

Allegedly, the U.S. Department of Defense Naval Air Warfare Weapons Division facility at China Lake, California tested a number of storage formats [pdf] for their vulnerability to excessive light, heat, and humidity, and only the M-DISC remained undamaged after the 26.25-hour testing period. True? Without launching a FOIA request, I can't find any source for this claim other than M-DISC manufacturers themselves and technology journalists who seem to be parroting M-DISC manufacturers. Furthermore, the "1,000 years" claim only seems to apply to the original 4.7GB M-DISC, not to industry-branded 25+ GB versions.

To complicate matters, the French National Laboratory of Metrology and Testing tested M-DISCs at 90°C and 85% humidity [pdf]. They concluded:

"Among the 7 models of disc examined only the GlassMasterDisc resisted to the accelerated aging at 90°C and 85% relative humidity for 1000 hours [...] The DVD+R with inorganic recording layer such as M-DISC and DataTresorDisc show no longer lifetimes than conventional DVD±R."

Digging a bit deeper, we can find the ISO/IEC 10995 certification [pdf] issued to Millenniata for their M-DISC technology. The cert states that the M-DISC managed a mean expected lifetime under 22 degrees C and 50% relative humidity of over 1,000 years, but the 95% confidence level is only 530 years. This means it is likely that only half the batch of discs makes it to 1,000 years, with 95% of them making it to 530 years. Well... lies, damned lies, and statistics.

It's also fair to ask whether any laboratory test is a reasonable simulation of the passage of 1,000 years. Who knows what conditions will be like centuries from now? Given the rate at which technology becomes obsolete, will any current optical media be usable even 20 years from now, much less 1,000? Can you still use a floppy disk from 1996, even if the disk itself is intact? I conclude that the "1,000 years" business is meaningless market-speak, not to mention statistically dishonest.

M-DISC vs. CDs and DVDs

Conventional DVDs or CDs are known to degrade over a period of decades, due to many different variables. The Council on Library and Information Resources maintains detailed information on this. They write:

"Among the manufacturers that have done testing, there is consensus that, under recommended storage conditions, CD-R, DVD-R, and DVD+R discs should have a life expectancy of 100 to 200 years or more; CD-RW, DVD-RW, DVD+RW, and DVD-RAM discs should have a life expectancy of 25 years or more. Little information is available for CD-ROM and DVD-ROM discs (including audio and video), resulting in an increased level of uncertainty for their life expectancy. Expectations vary from 20 to 100 years for these discs."

The persistent problem with optical storage is media that is mass-manufactured using suspect materials in less-than-optimal conditions. As long as you buy name-brand discs and don't expose them to Venusian temperatures and atmospheric pressure you should be all right for a couple of decades. Rules for data backups are the same as always: back up your data in as many places as you can stand to and don't abuse your media.

As for M-DISC, the only solution is to have yourself cryogenically frozen. 1,000 years from now, assuming the planet hasn't been nuked into a lump of carbon, you can have yourself revived, pull out the M-DISCs and reader you cleverly brought with you, and test your discs if they haven't all disintegrated. Then you can obtain whatever time-travel device is currently stylish, return to the present, and inform us of the results. We'd love to hear it, and while you're at it, bring me the next 20 Super Bowl winners.

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