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."
Nonsense! (Score:5, Interesting)
Record it to your HDD in an non-lossy format and store copies of it on various friends' and family members' computers. Back up frequently and your recordings won't suffer from the kind of decay and generation loss that analog tape does.
Re:Nonsense! (Score:5, Informative)
The only way to keep bits in any kind of order and in good condition over a long period of time with the kind of technology available to the average consumer is to keep making multiple fresh copies before each individual storage media begins to suffer loss of data.
Re:Nonsense! (Score:5, Funny)
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:Nonsense! (Score:4, Interesting)
Then obviously you couldn't have copied all the data to the "current" medium in the first place.
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:Nonsense! (Score:5, Funny)
They store all possible data at the same time, and when you need a file it somehow produces the right file.
However, he probably doesn't have enough cats.
Re:Nonsense! (Score:5, Funny)
Paper can last for thousands of years... this could be a good solution for long-term storage... right?
Re:Nonsense! (Score:5, Funny)
Encode your data into the DNA of Cockroaches!
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:5, Interesting)
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: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:As Linus Said (Score:5, Funny)
Re:As Linus Said (Score:5, Funny)
NIST Study (Score:5, Informative)
Re:NIST Study (Score:5, Informative)
Re:NIST Study (Score:4, Informative)
Re:NO JOKE (Score:5, Funny)
best bet... (Score:4, Interesting)
Reel to Reel WILL FAIL (Score:5, Interesting)
Add to that the cost of replacing r2r tech, and you've got a scary situation. I agree with the parent. CD may not be the answer, but digital sure as hell is. I'd be super paranoid having anything I cared about stuck on old tape.
Re:Nonsense! (Score:5, Informative)
Support for this stuff's not going to disappear overnight; you can keep specifications and reference implementations about if need be.
Re:Nonsense! (Score:5, Interesting)
Who's really going to remember this schedule?
This is my beef with digital photography: I found a negative for a photo that was taken sometime between 1891 & 1934 - prints were beautiful. This negative was not stored properly at all. No special effort to preserve.
With digital photography & CD-R disks I'm not so sure that we're not just creating a set of transient memories which will disappear into the ephemera in 10 years time.
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.
Re:Nonsense! (Score:4, Insightful)
Link [sourceforge.net]
CD Rot (Score:5, Interesting)
- If you can rub the top of a CD and have your finger come back silver, that's a bad sign. I avoid cheap CD-Rs. Sorry, CompUSA.
- I burn at 2x, always, unless I am burning something that I don't care about. Someone showed me the difference in color, I was convinced.
- Sticker on top = CD death.
- Take care of your media. Had a friend who left a CD on the windowsill and forgot about it. Many months later, you could see right through it. Nice corrosion.
I find it weird that anyone can stick a 100 year lifespan on a product that hasn't been around that long. I know that they have processes that supposedly accelerate the process and give you a rough estimate, but I am skeptical. Maybe they really are that durable, and people are just careless/cheapskates. You know what they say about malice and idiocy.
Re:CD Rot (Score:5, Funny)
While counselor at a computer camp, once I showed a kid how to rip the reflective face off a CDR with some duct tape, and he spread that information to all the kids. Little did they know that the dye underneath is toxic, and like 7 or 8 kids were puking up their lunch later on. I told the boss I had no idea what happened.
Burning at 2x... (Score:5, Informative)
Re:Burning at 2x... (Score:4, Informative)
I burn a lot of discs at max speed and they frequently won't run on OLDER pc's.
So when I KNOW I have to burn one for an old pc I burn it at 4x or 6x (with k3b) and it always works.
Re:CD Rot (Score:5, Informative)
If the CD feels sticky around the edges, it may (may) mean a low quality glue was used. It provides a potential path for fungus to migrate into your CD.
Gold reflecting layers (very rare to find anymore) are the absolute best. Gold generally doesn't react with the stuff in the atmosphere.
High quality archival stabilized dye layers are also hard to find anymore. Phthalocyanine was the absolute best last I looked (a few years ago) with an estimated stable lifetime of 200 years.
A CD that you want to hold data for 100 years should have a quality glue job, gold reflective layer and Pthalocyanine dye. I know of only two brands that have ever been made to this quality. One was Kodak Gold (some marketing suffix here), but it went out of production several years ago. The other is Mitsui Gold, which cost about $1 each in 100 packs.
And no matter how nice the CD manufacture is, it will not last unless properly stored. The three tenets of archival storage are: Cool, Dry and Dark. Don't leave your CD-R's on the shores of a tropical beach.
Re:CD Rot (Score:5, Informative)
I have to burn them at less than max speed, apparently the more stable dye requires more laser power. Otherwise no surprises so far. (knock on wood)
MAM-A "gold" metallized layer is aluminum not gold (Score:5, Informative)
Mitsui is claiming their _special dye_ is what makes their MAM-A discs last so long, and the dye is what gives their discs their gold color. Not the metallized layer.
And really when you think about it, it doesnt matter how long-lived the reflective layer is, if your dye deteriorates. Since you're recording your data onto the dye layer -- not the reflective layer.
Re:MAM-A "gold" metallized layer is aluminum not g (Score:5, Informative)
Re:CD Rot (Score:5, Informative)
Writing speed (Score:5, Informative)
This means that if you have a 2X recorder, writing at 2X is *much* better than 1X. If you have a 32X recorder, writing at 32X will produce measurably better discs than writing at 4X, 2X or 1X. This has been true since around 1998 or so. It is quite true that you could get better results with some early 4X recorders when writing at 1X than 4X. However, none of those devices are current any longer.
The "writing slower is better" story is a myth. Please don't spread it further. And yes, if you want more information about disc testing Media Sciences is a company that is dedicated to disc quality and testing. I do not work for them.
Re:Writing speed (Score:4, Interesting)
Re:Writing speed - audio vs. data (Score:5, Interesting)
Re:Writing speed (Score:5, Informative)
It is a popular misconception that burned PS2 games will not work if burned over 1x. The reason this APPEARS to be true is because a lot of DVD burners suck ass, even the big brand name ones. Burn anything over 1x, and the PS2 can't read the data.
Is it the PS2's fault? No. Reason being... I've witnessed DVD-Rs burned on 2.4-4x using a friend's DVD burner that will NOT play at all, but I take a DVD burned with MY DVD burner at 4x, it works perfectly! Same brand of disc and everything.
Based on that, I think it's safe to say that it all depends on what you burn it with.
Re:CD Rot (Score:5, Insightful)
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.
Using RIAA math (Score:5, Funny)
Solution! (Score:5, Funny)
Re:Solution! (Score:5, Informative)
punchcards are better (Score:5, Funny)
http://img53.photobucket.com/albums/v162/Cordat
As long as I keep them in a dark and dry place, it's going to last forever!
Doooom(esday)! (Score:5, Interesting)
Re:Doooom(esday)! (Score:5, Interesting)
Re:Doooom(esday)! (Score:3, Interesting)
date, reburn, rinse, repeat (Score:5, Interesting)
Blank CDs in bulk are cheap. For archival stuff I make a new copy every 5 years. I have a bunch of scanned photos I don't want to lose, so I re-copied them all onto new CDs.
You aren't supposed to write on the CDs either but I've not had any trouble with that, probably because I'm not trying to keep them very long.
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.
Eternal archiving. (Score:5, Funny)
Repeat every year with the current cover girls of Maxim, Stuff, or whatever men's mag suits your fancy.
Guarantee you'll never be at a loss for a copy of dear old granddad.
Re:Eternal archiving. (Score:3, Funny)
-m
Re:Eternal archiving. (Score:4, Funny)
Oh, sorry son. Wrong file. Don't tell your mother.
Re:Eternal archiving. (Score:3, Interesting)
Using P2P software, you supply:
a) n bytes of data you want archived
b) 10Xn bytes of free space to archive other people's stuff
So you've got 1GB you want preserved forever? Supply 10GB to the network, and the software takes care of the rest. If a user drops out of the network, his "stuff" is purged after 30 days of inactivity, freeing up space for new participants.
100-year shelf life, but 3 year usage life?? (Score:5, Informative)
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.
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.
Re:First of all... (Score:5, Informative)
Re:First of all... (Score:4, Interesting)
When a CD ages, and the surface scratches, and the ink degrades, the data doesn't fade to yellow and get wrinkled like a newspaper, or it doesn't sound like its being pumped over a telephone like a record would, it is just gone. At least with analog data (especially newspaper) there isn't this working/not working parity...we can see the degradation and recopy the data before its too late.
Of course we try to get around this by adding error detection/correction schemes, but I think the original post is about how (apparently) these aren't adequate.
Analog Audio is not a fair comparison (Score:5, Informative)
As the tape ages, the quality of the audio signal degrades dramatically, but because it is an analogue signal, it can still be deciphered by or ears.
With digital medium, the audio never gets worse. As the media degrades, it just reaches a point where it isn't able to be deciphered as audio data.
If you want to compare the mediums (magnetic tape vs. CR-R), data is probably a better place to do so. You can easily measure the amount of readable/unreadable data in bytes and make a fair, quantifiable comparison.
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).
Redundancy (Score:4, Informative)
Tape isn't going to last forever. At least when it's digital you can easily transfer to new media without loss of quality.
If it's really important you just need to make sure you keep ahead of obsolecence. Transfer the stuff to the new standard before the old standard completely goes away. There's always a transition period.
Ben
5 Years is accurate (Score:4, Informative)
Rather dissapointing the first time it happened.
seems to be from several big brand names, so it must be a limitation of the Dye, not just a bad batch.
But then again, it was designed to be written too ( i.e. physcially changed ) so how can one expect it to last forever?
You're citing Rense.com as an authority? (Score:5, Informative)
Re:You're citing Rense.com as an authority? (Score:5, Funny)
Do I have to wrap my por^H^H data archives in tinfoil now as well?
Another 6 months, another CD longevity article (Score:5, Interesting)
Besides the fact that CDs DON'T have a 100 year shelf life, we've also discussed the CD eating fungus several times here, which for people in hot and humid environments (particularly, it seems, Mexico, Central, and South America) can reduce a CDs lifespan to months or a couple of years.
And then you have the fact that rewriteables have an even shorter lifespan.
One thing that's rarely mentioned is the fact that most CDs are defectively manufactured. I say this because the metalic layer between the plastic is supposed to be sealed. But the fact that the aforementioned CD eating fungus enters through the two layers of plastic says to me that CDs are generally defective in that they fail to properly seal this layer.
I personally lost about 25% of my CD collection to this fungus over a 2 year period in Mexico, so I speak with some experience. These CDs were not abused. Most were in plastic cases, some were in sleeved carriers.
my first audio cds are dying (Score:3, Interesting)
Re:my first audio cds are dying (Score:5, Informative)
Pressed CDs shouldn't be as vulnerable to bit rot as burned CD-Rs. But I can't understand how the discs would lose quality. One either gets a valid frame of redbook audio or not. I can understand that some of the frames might go bad (even to the point where the built-in error correction can't help) and lead to audio defects, but I don't see how the whole disc would sound different than before.
Re:my first audio cds are dying (Score:3, Informative)
Why 100 years ? (Score:5, Interesting)
FUD (Score:4, Interesting)
Bottom line, buy cheap media then you will suffer the consequences. Buy decent media; buy a reputable brand and you can expect reasonable lifespan.
Hey, and wasnt this a dupe? albeit one with a twist ?
nick
Long term audio storage (Score:5, Informative)
They believe that this will preserve the audio for about 300 years and they say that vinyl is the only storage medium with a real and predictable life span.
Re:Long term audio storage (Score:3, Interesting)
http://en.wikipedia.org/wiki/Laser_turntable
8,000$ is just not within my disposable budget.
Archive the raw samples! (Score:5, Informative)
Audio processing technology will get better. Don't ruin your grandkids' heirloom recordings by using today's technology to permanently alter them.
Make working copies and filter those as much as you want, but keep those masters pristine! Maybe somewhere in the background you can hear your grandma yelling at dear ol' grandpa to put that thing away and paint the house, and a clumsy run with an agressive low-pass filter will throw that data away forever. You have something really valuable; please take care of it for the future.
The 100-year problem... (Score:3, Informative)
...is not that the CDs will decay and become unusable. The real problem will be that the file formats of today will be replaced in 10 years, and will be a legacy file format only readable with a compatibility layer in 20 years. In 50 years, that CD will be unreadable. Of course, storing it in ISO 9660 format would offer some protection. If nothing can read the CD 50 years from now, you could at least fall back to the standard spec write your own code to read it.
Oddly enough, I note that UDF is getting pushed as a replacement to 9660. So maybe even 9660 will be outdated faster than I expect.
Will CD drives exist then? I certainly can't get an old cassette tape drive these days, and that's only been 20 years. Hmm. I think in 100 years, the decay of your CD will be only 1 of many problems.
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.
CD tips for longetivity (Score:5, Funny)
Now, you can enjoy your CDs for a long time...
Simple (Score:3, Funny)
Go ahead and digitize everything. Then get yourself a couple of accounts at Gmail [google.com] when it becomes available. Then email the audio to yourself. You will have it forever then.
Of course you will see a lot of google adwords for Geritol [geritol.com] and Ben Gay [yahoo.com], but nothing is perfect.
Oblig 'Me Too' Post (Score:5, Informative)
Periodically check CDRs (Score:4, Informative)
When too much of my CD's surface has read errors, I make a new copy of the CDR. So far I've only had to do this for 3 of my discs over the past 6 years or so.
use gmail? (Score:4, Funny)
CD RW are better ??? (Score:3, Interesting)
I always thought that CD-R s are more reliable than the RW's and genrally back up my data to CDRs ( and of course CDRW are more expensive)
That does it (Score:5, Funny)
Commodore 64 Disks (Score:3, Interesting)
I found a very nice person who had a Commodore 1571 disk drive hooked up to his PC and was able to get the files off. I was really impressed that after sitting around for 15 years, the data was all completely readable.
I was also amazed to learn that when I was in junior high I was using a program called "SpeedScript" which I had typed in from a Compute magazine, and it had, to some degree, EMACS KEY BINDINGS!!! Holy crap, I had no idea that the emacs seed had been planted in my brain so early on
Brings up a good point about buying mp3s (Score:3, Interesting)
Longevity of analog content vs. digital content (Score:3, Informative)
The benefit of analog is that you can store the original content for a long time, perhaps even indefinately if properly cared for. Digital, so far, seems to suffer from a lack of "permanent" media onto which content can be written.
The big difference, however, is that with some effort it is not required to have long-life media for digital. Unlike analog content (which degrades with each generation of copy), digital content copies perfectly from one generation of media to the next. Sure, it'd be nice if you could just archive one physical copy and store it forever, but since we realistically cannot, it's pretty good that a perfect copy can be made before it degrades.
Think of it this way: for decent preservation of analog content, you must exercise excellent dilligence in physical care; for perfect preservation of digital content, you must exercise regular, but rare dilligence in copying to a new media.
Besides, even if a "permanent" media is created for digital content, that's no guarantee that years from now the content can even be read. What good is it for your great-grandchildren to pull out your CD-ROMs 100 years from now, and have them find that no-one has manufactured compatible devices for over 80 years, and no one has serviced one for over 50 years? That data is just as lost as it would have been if the CD had degraded.
* Yes, I also know that today's paper is unlikely to last very long (relatively speaking), either. The papers used centuries ago withstand the aging process much better than your standard photocopier paper will.
CD-Rs can last longer (Score:5, Informative)
Second, the biggest mistake most people make in CD archival is to write on the CDs with magic marker -- DO NOT DO THIS. The ink will, given several years, leach through the extremely thin plastic on the labelled side of the CD and pollute the optical layer, resulting in a ruined CD. Adhesive stickers, I'm told, are not much better. There are special CD-labelling markers out there, I don't know if they work well as I haven't tried them, but I doubt they're worse than a magic marker. I have found that writing very lightly with a soft, dark graphite pencil works well. If you're very paranoid, you might consider not labelling the CD at all and just be meticulous in returing it to its (properly labelled) case when you're done.
Additionally, store the CDs properly. Somewhere reasonable. Not in direct sunlight. Safely stowed in their jewel cases.
Of course, even doing all this, no one can tell you that your CDs will still work in 100 years. It hasn't even been 100 years since we invented the damn things, how do we know how long they will last? Still, these are steps that should allow your CDs to last for at least as long as a magnetic tape, and with perfect accuracy, as opposed to the slow degradation of audio tapes.
What we really need is something similar to the S.M.A.R.T. technology in harddrives nowadays, to alert you that "Listen, I'm getting close to reaching the limit of my error-correction techniques here. This media probably isn't going to last a whole lot longer. You may want to do something about that." Currently, there's really no way to tell until it's too late.
Re:CD-Rs can last longer (Score:5, Interesting)
I wouldn't be so keen on having particles of electrically conducting graphite being spun off the disc inside the drive... But you're right that it probably won't damage the disc.
If you're very paranoid, you might consider not labelling the CD at all
Or write in the data-less area around the center of the disc.
The Sharpie rumor again (Score:4, Interesting)
Got some studies supporting that? I did my own little study after highly doubting this rumor. Here's how I think the rumor got started:
1. Buy cheapest Taiwanese media
2. Write on it with a Sharpie
3. Down the road, blame the Sharpie for media failure
My (unscientific, but the only data point I'm aware of) test:
In 1996, I wrote all over a Japanese Taiyo-Yuden made, unbranded Sony CD-R. In 2003, I tested the data, which was fine. I then cleaned the Sharpie ink off the disc with carburator cleaner (harsh treatment, for sure). It wiped off in seconds with no trace whatsoever, so in 7 years the ink did not migrate into the disc at all. After this, the data was still good.
Conclusion: Buy good media and quit worrying about writing on the discs. They'll take it fine, and if they die, it wasn't the pen that killed them.
People are cheap (Score:5, Informative)
Want a long lasting CD-R? Search the spindles to find the ones that are made in Japan. Sometimes these will be on the same shelf with the Taiwan ones, wearing the same packaging, and for the same price (if you're lucky). Usually these are made by Taiyo-Yuden, a high-quality CD-R manufacturer (and one of the co-developers of CD-R technology). Look for a frosted hub for positive ID.
For archival quality, you'll need to spend a couple of bucks a disc on media that has a gold reflective layer. The standard here has always been Mitsui (now branded as MAM-A). Even their silver discs are a cut above in quality.
Oh, while I'm here. In 1996 I scribbled all over a burned CD-R with various colored Sharpies, then last year cleaned it all off with carb cleaner. It hadn't migrated into the disc at all, and cleaned off without a trace. The data was fine. Anyway, I mention this because I hear people claim Sharpies kill CD-Rs all the time, and think it's nonsense. These people probably bought the cheap-o discs and are looking for something other than their own cheapness to blame it on. Oh, BTW, the scribble disc was a Sony, made by Taiyo-Yuden.
Risk of data loss for nth generation copies? (Score:4, Interesting)
BIG HONKING HARD DRIVE!! (Score:3, Funny)
Yes, I can imagine a Beowulf cluster of these...
Andy McFadden's CD-R FAQ says... (Score:5, Informative)
(2004/02/17) in CD-Recordable FAQ [cdrfaq.org]:
CD-RWs are expected to last about 25 years under ideal conditions (i.e. you write it once and then leave it alone). Repeated rewrites will ccelerate
this. In general, CD-RW media isn't recommended for long-term backups or archives of valuable data.
The rest of this section applies to CD-R.
The manufacturers claim 75 years (cyanine dye, used in "green" discs), 100 years (phthalocyanine dye, used in "gold" discs), or even 200 years
("advanced" phthalocyanine dye, used in "platinum" discs) once the disc has been written. The shelf life of an unrecorded disc has been estimated at
between 5 and 10 years. There is no standard agreed-upon way to test discs for lifetime viability. Accelerated aging tests have been done, but they may not provide a meaningful analogue to real-world aging.
Exposing the disc to excessive heat, humidity, or to direct sunlight will greatly reduce the lifetime. In general, CD-Rs are far less tolerant of environmental conditions than pressed CDs, and should be treated with greater care. The easiest way to make a CD-R unusable is to scratch the
top surface. Find a CD-R you don't want anymore, and try to scratch the top (label side) with your fingernail, a ballpoint pen, a paper clip, and
anything else you have handy. The results may surprise you.
Keep them in a cool, dark, dry place, and they will probably live longer than you do (emphasis on "probably"). Some newsgroup reports have complained of discs becoming unreadable in as little as three years, but without knowing how the discs were handled and stored such anecdotes are
useless. Try to keep a little perspective on the situation: a disc that degrades very little over 100 years is useless if it can't be read in your
CD-ROM drive today.
One user reported that very inexpensive CD-Rs deteriorated in a mere six weeks, despite careful storage. Some discs are better than others.
An interesting article by Fred Langa (of http://www.langa.com/ [langa.com]) on http://www.informationweek.com/story/showArticle.j html?articleID=15800263&pgno=1 [informationweek.com]
describes how to detect bad discs, and discusses whether putting an adhesive label on the disc causes them to fail more quickly.
By some estimates, pressed CD-ROMs may only last for 10 to 25 years, because the aluminum reflective layer starts to corrode after a while.
One user was told by Blaupunkt that CD-R discs shouldn't be left in car CD players, because if it gets too hot in the car the CD-R will emit a gas that can blind the laser optics. However, CD-Rs are constructed much the same way and with mostly the same materials as pressed CDs, and the temperatures required to cause such an emission from the materials that are exposed would
melt much of the car's interior. The dye layer is sealed into the disc, and should not present any danger to drive optics even if overheated.
Even so, leaving a CD-R in a hot car isn't good for the disc, and will probably shorten its useful life.
See also http://www.cd-info.com/CDIC/Technology/CD-R/Media/ Longevity.html [cd-info.com],
especially http://www.cd-info.com/CDIC/Industry/news/media-ch ronology.html [cd-info.com] about some inaccurate reporting in the news media.
See "Do gold CD-R discs have better longevity than green discs?" on http://www.mscience.com/faq53.html [mscience.com].
The embarassing part... (Score:5, Funny)
Is that I can still read data from Iomega Zip disks that are 6 years old, yet can't read CD's I burned 6 months ago. For some reason, the perils of magnetic media and Zip drives never came true for me.
What really irks me is that CD-R was sold to the public as a way of _permanently_ archiving data. Once written, it was supposed to be permanent. The non-magnetic, non-rewritable nature of the media was supposed to prevent accidental overwrites and erasures from magnetic fields.
Top Ten reasons to love CD-R/CD-RW:
* - yes, these are the recommendations that came with a 2004 Toshiba laptop regarding making CD's.
Magneto Optic (Score:4, Interesting)
Re:Or.... (Score:5, Insightful)
Re:Or.... (Score:5, Funny)
So i guess someone was paying attention in Stats class ;)
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
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: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.