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The Myth Of The 100-Year CD-Rom
Toshito writes "Are we putting too much faith in the ubiquitous "recordable CD", or CD-R? A lot of manufacturer claims 100 years of shelf life for a CD-R. But in real life, it can be much less. Expect failure after only 5 years... Personnaly I just discovered 6 audio cassettes with the voice of my late grandfather, talking about old times. These tapes are copies of reel to reel recorded in 1971, and they are still in excellent shape.
I was thinking about digitizing everything, do a little noise reduction, and burning this on CD's, for my childrens and great grand-childrens enjoyment, but it seems that old analog tech from the '70 is more reliable than digital. The full story at Rense. Other links about the subject: Practical PC, Mscience, and an excellent reasearch by the Library of Congress (warning! PDF): Study of CD longevity, html version (google):Study html."
But be sure to use blanks from different manufacturers. Otherwise your failures won't be independent, so the odds of all your copies going bad at roughly the same time (i.e., before you notice the first one has failed) is high.
The danger in "old" storage formats is lack of machines to read them. Those tapes may be in good shape, and so might the data on an 8" floppy I have, but the 8" floppy is effectively lost to me because I don't have easy access to a drive that can read it anymore! The paper tape programs I "printed" out from a VAX PDP-11 are probably good (if I hadn't lost them years ago) but I can't get to a tape reader, etc.
You almost have to make dozens of copies of data on a modern cheap format, and keep moving it forward.
How do you know there is no loss with analog?
Analog quality loss is acceptable, because it results in static. Digital loss isn't acceptable, because (at least practically) it is a binary property...the CD works or it doesn't. Scratch the hell out of a record, and at least you still have something.
We could build acceptable redundancy into digital backups, its just that most people think of it as wasteful. You know what though?... I have everything worthy of backup "backed up" in at least 3 places, one of which is always CD stored somewhere out of reach. Digital is better. Once you convert to digital, you can have zero quality loss with near 100% efficiency, you just have to want it that bad.
In the wrong conditions, such as sunlight, humidity and upper surface damage, your CD-R will slowly turn into a coaster. "CD-Rs should never be left lying in sunlight as there's an element of light sensitivity, certainly in the poor quality media," says Stevenson. "I wouldn't rely on CD-Rs for long-term storage unless you're prepared to deal with them as recommended."
Surely storing cd's correctly is the key, if the dye on a cdr fades after being kept in a jewel case at a room temperature fr 2 years then that is obviously very bad (and there could be some lawsuits in the future).
Whether CDs last a long time or not is really missing the point. The benefit of going digital is that the data can be backed up.
If you're oriented on the media you're forever on the upgrade path. Should you move the collection to DVDs? But wait, blue light DVDs are right around the corner. It will never end.
120Gbyte hard disks are getting cheap. This trend will continue. What you store something on will literally become unimportant. The only important thing that will remain is still: how well is it backed up?
I still have perfectly working music CDs from the late 80s.
I have data CDs from the early 90s that are fine also
I just dug up some CD-Rs I burned from 1998 and they were fine also.
I think CDs can last a long time, but just like everything else...you need to take care of them. If it's something you use all the time, make backups and use those.
It's not time that kills CDs...it's scratches and wear.
"Some things have to be believed to be seen." - Ralph Hodgson
What happens when the amount time it takes to transfer all the data from one medium to another is longer than the life time of the media on which it currently resides?
Then obviously you couldn't have copied all the data to the "current" medium in the first place.
Burning at slow speeds is still a good way to ensure more players can read a CD. This technique does work, and I used it again just last night. I burnt an SVCD of a *cough* movie I found umm, somewhere in a cupboard, at the rated speed of my medium which was 10x (rewritable). The DVD player rejected it, unable to read the data. I burnt it again from the same .bin file at 4x and the DVD player read it perfectly. It may not matter when you read it back on the same drive you burnt it on, but it sure can matter when you want to hear it in your car or watch it on your DVD player.
All those moments will be lost in time, like tears in rain.
Not quite. The difference is robustness.
The negative may have had a small crease, or off-color spot or three (i.e. "bit" decay), or even be torn in half, but the basic information was intact.
The problem is that for many electronic storage formats, copy fidelity is strong but robustness (tolerance to a few corrupt bits, eg. in the FAT, or a plain an simple crack) is low.
So what's a robust way of storing gigabytes, so that the corruption of a few makes a few "off-color" pixels but doesn't destroy the image overall? Give me a format that I can still read most of it, with no crucial weak spots (eg FATs) even if a few words are smudged or faded. That's why papyrus works.