CDs, DVDs Eyed For Long-Term Archival Use

Alien54 writes "Computer scientists at the National Institute of Standards and Technology (NIST) are launching an effort to develop specifications for 'archival quality' CD and DVD media that agencies could use to ensure the procurement of sufficiently robust media for their long-term archiving needs (i.e., 50 years and longer). See the press release at the NIST site." The research involves "...enclosed chambers that use temperature and humidity changes to artificially age the media some 20 years in only six weeks."

Comments

Re: CD decay rates

[some guy I know]

This recent article in The Register refers to a test by a Dutch magazine called PC Active.
They tested 30 different brands of CD that had been recorded only 20 months earlier.

"Several data CDs developed serious errors, or became virtually unreadable."

Here is a picture of one of the CDs.
The red area can no longer be read.

This is pretty hideous.
I use CDs for archival storage.
It looks like it will become necessary to copy everything to new media every year or so, lest it become lost, forever lost, never to be seen again by the eys of mortal man.
It's very annoying.

This problem has already been solved

[treat]

If you're a sysadmin, this problem has already been solved. RAIDed hard drives, always on, read occasionally to check for errors, and drives replaced as they fail. Replace the drives with new models every so often (or as they fail perhaps). Replace the controller and system it is attached to as necessary.

That is to say, that no digital storage that exists outside of a lab is suitable for long-term archival. Luckily, digital data being so easily copied (how easily people forget this!) makes this an easy problem to ignore. If you're developing new types of media, great. Otherwise, there is only one practical solution.

Yes, "my" solution - the solution used by anyone who has digital data they want to store long-term - requires someone to babysit the data. Sorry, most things in this world need some kind of human maintenance.

If you're storing the data on hard drives attached to a working computer, you can mirror the data on the other side of the world to protect it against any catastrophe that humans will survive.

If you don't care about a practical solution that has by far the highest chances of success, feel free to speculate about how long CDs will last based on completely invalid lab testing. (Accelerated aging? Hah! How can they possibly account for every variable?) If you truly care about your data, keep it online and make sure someone is around to maintain the system. If you want something less, it's because you don't actually care about the data that much.

My findings

[Mxyzptlk]

This is quite interesting - I'm looking into CD archiving quality right now, because I have to transfer my grandmother's story of her life from ordinary tapes to something more persistent.

Some things I've discovered so far are:

• The swedish national archive recommends Kodak Gold Pro for archiving purposes. However, Kodak seems to have stopped selling them...
• Gold CDs are better than silver CDs. The worst kind of CDs are the ones that you can see right through, if you hold them to a lamp.
• You should store your CDs in their original packaging, if available. That is: store them in a hard plastic package, and avoid soft paper or plastic. Store them upright, in 22% humidity and 5 C (66 F).
• Avoid humidity and light as the plague - even a couple of minutes of sunlight can have a great effect. If you are really paranoid, then you should use clean cotton gloves when you are touching your CDs. Of course, scratches, finger prints as such are not good...
• You should use CDs with less storage space, because the bigger the room each bit has, the less risk is it that that bit can be destroyed.
• If you must write something on the CD, then write as near the center hole as possible, and use you smallest handwriting. The color of the pen can actually affect the reading capability of the data, although the data is on the opposite side of your text.

The biggest problems seems to be that the CDs come and go, so it can be difficult to get the tested products. The tests that has been done has used "accelerated aging", which is just a simulation. That is, there is no real experience in aging CDs.

My advice would be to store valuable information on as many different formats as possible. Continually monitor the quality of these, and transfer to new backups when they start to degrade too much.

Hope this helps!

Re:Digital Short-comings

[njj]

One common criticism of the use of vellum is that of animal cruelty, although it's worth noting that the goatskin used is a by-product of the leather industry, and comes from goats that had already been slaughtered to make, say, shoes.

I was glad to hear that this latest attempt at pointless `modernisation' (for the sake of appearing `modern' rather than for any deeper and more sensible reasons) was defeated. Not least because it's really cool to be able to say ``This is actually an Act of Parliament from the 16th century, and that's actually Henry VIII's signature - not a photocopy, not a JPEG, but the real thing.''

A related matter concerns the increasing prevalence of digital photography. As this BBC News article explains, digital photography may cause problems for future generations of local or family historians. Proper (printed) photographs tend to get stored away in shoeboxes in attics, and are still more-or-less as legible after a hundred years as they were when they were taken. Whereas an entire collection of digital photographs can be wiped out by one hard-disk failure.

Or maybe in fifty years' time nobody'll know how to display a JPEG. Somewhere I've got a tape with the very first program I wrote, recorded on it. It was a simple bullseye game for the Video Genie II (a TRS80 clone) - it wasn't particularly sophisticated by general standards, but not at all bad for an eight-year-old kid. I have no means of retrieving it on any of the small menagerie of computers currently in my house.

Another, related, example: in the mid-1980s a (for the time, pretty damned impressive) multimedia project was launched - the Domesday Project. This was a laserdisc containing digital reproductions of the original 11th-century Domesday Book itself (a census survey of the entirety of England ordered by William I) together with (I think) the 1981 national census data. All very innovative (albeit rather a costly system) but ironically, 15 years on, the laserdiscs are not readable by current technology - but the original 900-odd-year-old Domesday Book itself still is.

I guess the point is that it's all very well saying ``this media is guaranteed to last for fifty years'' (although personally I'd be happier with something that'll last several hundred) but also you have to guarantee that the data format itself is going to remain readily decodeable. This is not a problem for 1000-year-old documents on vellum (as long as your Latin or Norman French is ok, and you've done a basic course in paleography).

nicholas