The Myth Of The 100-Year CD-Rom 671
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."
Or.... (Score:1, Insightful)
Re:Or.... (Score:5, Insightful)
Old formats require old machines (Score:5, Insightful)
You almost have to make dozens of copies of data on a modern cheap format, and keep moving it forward.
First of all... (Score:5, Insightful)
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.
Storage Conditions (Score:5, Insightful)
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).
Re:Nonsense! (Score:5, Insightful)
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?
Re:100-year shelf life, but 3 year usage life?? (Score:5, Insightful)
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.
Redundant hard drives is my solution too (Score:3, Insightful)
I have a big honkin hard drive 120gig with all my stuff at home. I have a 2nd big honkin 120gig that has USB2. I take the USB2 drive to work once a month and leave it there. Bingo--off-site backup solution. (Yes, encrypted file system so co-workers can't browse my comprehensive porn collection.)
The stuff that changes more often (like photos) that I couldn't really bear to lose I rsync to my linux box over the net.
Everything fails, redundancy is the way to go. And it has to be easy.
Re:Free Biz Idea (Score:4, Insightful)
Better get some great insurance, I wouldn't want someone to have their 1850's relatives diary destroyed and then find out that I also lost their only digital copy!
Re:CD Rot (Score:2, Insightful)
But,
did YOU happen to know that the dye was toxic?
Re:Nonsense! (Score:5, Insightful)
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.
Re:date, reburn, rinse, repeat (Score:3, Insightful)
Losing and then finding media is of course the real problem as lost digital recordings do not get refreshed and may be destroyed.
Re:The BEST CD-R brand? (Score:3, Insightful)
It is the same dye system that Kodak used in their Gold Ultima that is unfortunately no longer manufactured. Kodak licensed the technology from Mitsui.
Re:CD Rot (Score:5, Insightful)
Re:Nonsense! (Score:3, Insightful)
As for archiving, where I work data needs to be kept for 7 years and then can be destroyed. If I could get the media to last for 7 years and then be unreadable, that would be ideal!!
Re:Nonsense! (Score:4, Insightful)
Well, yes, but every so often, a format comes along that works, is cheap, and enjoys widespread use and support. CDs were the last one. Eventually, the multiplicity of DVD options will coalesce around one of them. After that, we can bitch about the next gen of data storage here on Slashdot.
Re:Nonsense! (Score:3, Insightful)
CD-R's are for daily/frequent use.
For serious archiving, keep copies on multiple hard drives. Tools like
rsync [anu.edu.au] make this very easy.
Re:CD Rot (Score:4, Insightful)
Informal testing shows that the silver-green dye lasts about 6 months in a hostile environment (namely the visor in my car- and I live in FL). The dark blue has lasted upwards of 6 years.
if you don't trust digital... (Score:3, Insightful)
Re:Nonsense! (Score:5, Insightful)
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.
digital copies last through transfer (Score:3, Insightful)
But another points is, why would you want to keep something on CD for a hundred years? You can't walk into a Walmart and buy a record player. 100 years is probably more than the lifespan of the medium, regardless of how long each disc is expected to last.
Re:Nonsense! (Score:4, Insightful)
Link [sourceforge.net]
Statistics and lifetime... (Score:3, Insightful)
The actual life of any specific item depends on many factors: manufacturing quality, manufacturing materials, storage, number of plays, etc.
So, while it is fair to say that "audio tape" is a relatively short-lived, fragile medium (based on the average "audio tape") it is not unusual to have tapes that last 30 years without noticable degradation. I've had tapes that didn't survive the first pass through the recorder, because they were made with crappy glue holding brittle magnetic bits. I have tapes that I've kept in a box for twenty years that are just fine.
You'll find the same thing for CD's. If you use good quality CD-Rs, and store them correctly, I have little doubt that 100 years is a reasonable expected lifetime.
And as others have already pointed out, if the recording is really important, make multiple copies, and then make new copies from the old before they degrade. In this case, CD-R has it over tape, because each generation of tape gets worse, while each generation of CD-R is identical to the parent.
Re:Nonsense! (Score:4, Insightful)
Not true. The data could have been collected and recorded on the current media by multiple field sites, which may no longer exist, may have upgraded their recording equipment, or be too busy with current data collection projects to dupe media. You can easily end up with many thousands of tapes in a warehouse and insufficient equipment and time to copy them to new media before they rot. That's assuming you can get the funding for the work in the first place.
Re:The 100-year problem... (Score:4, Insightful)
Not just the format of the file system (your example), but the format of the individual files. Does anyone believe that, outside of a handful of people in museums, anyone will be able to read GIF files in 100 years? Or MPEG-1 compressed video? Or documents stored as Microsoft Word 97 files? I've worked with computers for the past 25 years, and have encountered all of the problems that people have mentioned in this discussion: tapes for which there are no drives available, tapes and disks which degrade to the point that they are unreadable, file systems on disks that are not supported by contemporary OSs, and individual file formats for which no software (or specifications) exist. I also have a box filled with the paper copies of 25 years' worth of writing, and even the oldest are in good shape and WORK. If they were especially valuable, I'd make another paper copy and put it in the safe deposit box at the bank.
Audio and video are more difficult, since there's nothing as good as paper for them.
Re:Nonsense! (Score:1, Insightful)
Re:Nonsense! (Score:2, Insightful)
Exactly right. But when the value of the media (CD-Rs, HDDs, etc.) is less than the value of the data stored on the media, it's not hard to justify. This is the difference between bits and atoms. Atoms are mostly worthless -- bits can be invaluable.
Correct. With analog media, each succeeding copy represents a breakdown in quality of the data, but there is no difference between an digital original of data and its digital copy. After a digital copy is reliably made, it is just as accurate as the original, and can be used as such.
WIll the data format be readable in 100 years? (Score:2, Insightful)
Whos to even say that the file format will still be supported long into the future as well.
Makes me wonder about thoses old Apple//e games I used to have on 5.25" discs.
I miss Hard Hat Mac!
Why tape works (Score:2, Insightful)
What is needed is special encoding, reading, and algorithms that are more tolerant of degradation. However, it will probably take up more storage space, but that may be the tradeoff for longevity.
Tape tends to have redundancy in the lower frequencies, and this is partly why it seems less fragile. Perhaps something similar on the digital side can be done.
I notice that our VCR tapes are more kid-proof than DVD's. The kids play with both innappropriately, and the VCR tapes have about a 3-to-1 survivle rate over DVD's. I would have never guessed this without seeing it in action because VCR tapes have seemingly fragile moving parts and more parts. Go figure.
Re:Nonsense! (Score:4, Insightful)
"Hey, if you make 8-dot chunks of the dots on these pages, there is a 256-element field such that every 255 chunks, when considered as a polynomial and evaluated at a particular set of elements, gives zero for all of them, on every page." "Eh, it's probably just an incredible coincidence."
Re:Nonsense! (Score:2, Insightful)
Re:Nonsense! (Score:3, Insightful)
The human brain?
Re:What kind? (Score:3, Insightful)
The quick reference is not really a standalone document. It is the summary of the longer PDF that assumes you have already read the longer doc.
What the longer document says is that my cherry-Kool-Aid-smelling Sharpie would be in the "aromatic organic solvent" category that should not be used.
Alcohol substitutes are also a solvent that should probably not be used, but aren't nearly as bad.
The recommendation is for the use of water-based markers.
Comment removed (Score:2, Insightful)
Re:data lost over time, it's normal (Score:2, Insightful)
they did (Score:3, Insightful)
they may not be any longer lasting though - the only answer is archive and periodically read and rearchive to the latest storage medium.