Archiving Digital History at the NARA

val1s writes "This article illustrates how difficult archiving is vs. just 'backing up' data. From the 38 million email messages created by the Clinton administration to proprietary data sets created by NASA, the National Archives and Records Administration is expecting to have as much a 347 petabytes to deal with by 2022. Are we destined for a "digital dark age"?"

Comments

Re:Answer is Compression?

[MasterC]

The only thing that comes to mind is information entropy. If you're given a text document, you can determine the probability distribution for each letter, letter combinations, for words, or whatever you can think of. Then given the probability distribution, you can determine the information entropy. If, in the sum, you use log with base 2 then H(x) (see formal definitions) gives you the entropy in bits.

For example, if you have a text file with letters of equal probability (all letters have a probability of 1/27) then the bits required to represent a single letter turns out to be ~4.7549 bits. (Indeed, 2^4.7549 = 27)

This is the upper limit of compression. Such methods as the, now 50-years old, Huffman coding do decent work at approaching this limit (used in JPEG, for one).

So the answer to your question is: it's not broadly definiable for "text" or "information" but based on the patterns of the English language or a specific document.

I'm guessing... steady state.

[dpbsmith]

The Zapruder film was the beginning. In recent years, I've been dumbfounded by the vast extension in recording and documentation of things like crimes in progress, natural disasters, America's Funniest Home Videos, you name it. A plane crashes, and the next day there are ten different home videos from people in the vicinity who had camcorders.

I believe the cost of traditional photography in constant dollars dropped enormously between my parents' time and mine. I know we took about ten times as many silver-on-paper and Kodacolor dye-on-paper snapshots as my parent did. Then we got a camcorder. My parents captured about three hours total of 8 mm silent home movies. I have about forty hours of 8mm and digital-8 camcorder tape.

And since my wife and I got digital cameras, we've been taking five to ten times as many pictures as we did when we used film cameras.

Now, YES, I'm on the format treadmill. Got most of the old 8mm movies transferred to VHS. Got most of the VHS transferred to DVD. Got a lot of the old slides scanned. Got most of my digital images burned to CD. In the last five years, I've probably spent a hundred hours, or 0.2% of my life, on nothing but struggling to copy from old formats to new. I've spent a small fortune getting Shutterfly to print pictures, because to tell the truth I have much more faith in the prints surviving than the CD's.

So, I don't see a digital dark age. I see a bizarre situation in which the quantity of material recorded in digital form continues to increase exponentially for quite some time. _Most_ of it will get lost, and the percentage that survives, say, a hundred years will keep going DOWN exponentially with time.

But I'm guessing the total quantity of 21st century material available to historians of the 23rd century will, in absolute numbers, be just about the same as the total quantity of 20th century material.

It's one of those mind-boggling things like personal death that one can never quite come to grips with. The future is unknown, and we can accept that. But the fact that most of the past is unknown is equally true--and very hard to accept.