Preserving digital media across the ages

edward - 10:10am Sep 5, 2006 PST

At 12:28 09/02/06 -0700, johnbaxterlistsmac.com wrote:

"Passive digital archiving" can't work.

I agree, but ...

it doesn't MATTER whether a DVD lasts in readable form for 10 years or 50 years--it will be necessary to move the data before then anyhow.

I wouldn't count on anything being readable for longer than I can keep my eye on it -- look how quickly it became difficult to read a floppy disk (much less an 8" floppy).

OTOH, the level of usage of a format, and the way it's used, do matter. And I would not by any means bet on CDs being unreadable in 50 years, or even DVDs. (Digital tape and disk are a different matter. Sell or discard your tape drive, copy your tapes! Don't even THINK about them lasting ten years.)

Look at CDs: the format is almost 25 years old, and the very earliest ones manufactured are still easily readable -- not just by finding the right player, but on any player. These of course are audio CDs. But audio CD is a digital format, and as long as the audio CD format is widely used, data CD readers will be around.

DVDs are nearly as widely used. The number of movies commercially available on DVD must be closing in on 100,000. (The last time I looked, Netflix claimed to carry 65,000.) They'll be around for a while, though in their present format perhaps not as long as CDs (see below).

The key to both of these is that they are 1) widely used by non-technical consumers, and 2) fit human scale in important ways.

That second part is important. CDs are low-density by modern standards, yet there is no move to change audio recording significantly. Why? Because the quality of the sound is already better than most human ears can distinguish, and the length is comfortable for humans: the length of a CD is longer than most concerts go without an intermission. Those who sell recordings haven't much if any motivation to sell in larger clumps, because getting the same return would require persuading consumers to fork over more dough at one time. In fact, since the Great Depression, I would say there have been only three major advances in recording: LPs, tape, and CD. Four-channel fizzled; it didn't matter to most people. Stereo exists mostly because the record companies could do it, not because consumers clamored for it. Those three advances addressed length, quality, and portability. What's left to dislodge the CD? (iPod is more portable but shows little sign of being enough of a portability advance to dislodge the CD in general)

DVDs have length and portability. They don't quite have quality, and HD DVD may replace quite a bit of the market. Will it replace regular DVD sufficiently to make reading a regular DVD difficult? I'm a bit less sanguine about it than about CD, but a couple of arguments say that regular DVD will at least be readable. First, as a medium with the same physical specs and very similar reading technology, it will be standard for HD DVD readers to read regular DVDs as well; there just won't be any economic incentive to remove this ability. Second, look at Betamax vs VHS ... a great many people just don't care that much about video quality. I look forward to HD DVD, but it may succeed mostly for the same reasons that stereo audio recording did: it was possible, so we sold it.

But I'm archiving actively. The big question is, how do I set up my archives to survive my death? That box of photos in the garage may have faded some, and we may have trouble identifying the subjects, but some of those photos survived. (When my grandmother died a few years ago, we found a basket of photos in her garage, some well over 100 years old -- older than she was, and she was 93.) Can I endow a web site -- pay an up-front fee to a company to preserve my web site into eternity? What will eternity mean when the Web17.1 standards emerge a century from now? Could I similarly endow a certain amount of storage on Amazon S3, guaranteeing the preservation of the bits though not necessarily of the software to make them meaningful? What *is* eternity?

Edward Art works by Melynda Reid: http://paleo.org