Most Digital Content Not Stable

brunes69 writes "The CBC is running an article profiling the problems with archiving digital data in New Brunswick's provincial archives. Quote from the story: 'I've had audio tape come into the archives, for example, that had been submerged in water in floods and the tape was so swollen it went off the reel, and yet we were able to recover that. We were able to take that off and dry it out and play it back. If a CD had one-tenth of one per cent of the damage on one of those reels, it wouldn't play, period. The whole thing would be corrupted'. Given the difficulties with preserving digital data, is it really the medium we should be using for archival purposes?"

Comments

Re:Multiple identical copies?

[t00le]

Any good backup strategy will have multiple media types, so CD/DVD should not be your primary backup media type. If you prefer to have an medium for fast access, then it is still viable. As long as it is not your primary media type, which should be something with tried-and-true longevity.

wring recovery method

[Red Flayer]

If a CD had one-tenth of one per cent of the damage on one of those reels, it wouldn't play, period.

That's because you're trying to optically read through the damaged part. It is possible to recover data from damaged discs, as long as only the coating (and not the reflective surface) is damaged. It is quite possible to polish the surface and read the data, or even to fill in some of the damage and repolish for reading.

Just because it's harder to recover the data doesn't mean it's impossible.

Of course, anyone using CDs or DVDs for large data backup must have a lot of interns to do the disc swapping.

Re:wring recovery method

[Criffer]

Exactly. If you try to put a bent CD into a CD drive, you're obviously not going to be able to read it. But that doesn't mean its not recoverable.

To recover data from a CD, you can simply photograph it at high enough resolution. Even with huge scratches, even with parts of the disc physically missing, you can recover the data exactly as it was encoded. How? Reed Solomon code .
Quoth wikipedia:

The result is a CIRC that can completely correct error bursts up to 4000 bits, or about 2.5 mm on the disc surface. This code is so strong that most CD playback errors are almost certainly caused by tracking errors that cause the laser to jump track, not by uncorrectable error bursts

have people already forgotten?

[phantomfive]

Have people already forgotten the advantage of digital? If you have an analog tape, every time you make a copy of it, the quality will be degraded. But with digital, you can make a million copies and the final copy will be the byte by byte equivilent of the original. So what if CDs only last 10 years before becoming unusable? You can make another copy! So what if this guy wouldn't have been able to recover after physical damage to his media....if it was important, he should have had digital offsite backups! And those backups would have been 100% equivelent to the originals.