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."
real story from the independent (Score:2, Informative)
100-year shelf life, but 3 year usage life?? (Score:5, Informative)
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.
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.
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:CD Rot (Score:5, Informative)
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.
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.
CDs can last for 100 years. (Score:2, Informative)
If your CDs are store in a cool dry place, out of direct sunlight they can certainly last 100 years your cassettes probably can too.
Whatever happened to backups (Score:2, Informative)
With disk space being so cheap now I keep a copy of all of my important data on my server, mapped drives to connect etc. I then have a login script that runs on a workstation and backs that data locally to the workstation (now I have two copies) - Windows users can use Robocopy and *nix users have rsync, both of these tools are exceptional and only copy the newer/changed files so the backup of 50+ gigs of data seldom takes more than 15 minutes.
I then back that up to one of two external hard disks, one of which is always in a safety deposit box.
CDs never were and never should have been a good backup solution. The technology will change. A good backup solution is one that changes with the technology. I know that these external drives will one day be obsolete but to there is no degradation of data like a CD that has flakes falling off of it after 2 months.
It's also far more cost effective and as I upgrade my computers over time I know my files will be updated too and when the tech moves beyond external hard drives I'll change the solution then. Backing up to CD once like that is asking for trouble if you never test the media, like I do on a daily basis, I still have old school assignments from 10+ years ago, pictures and business data that I know I will never lose.
John the Kiwi
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.
Burning at 2x... (Score:5, Informative)
Re:Solution! (Score:5, Informative)
Re:First of all... (Score:5, Informative)
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.
NIST Study (Score:5, Informative)
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: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: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.
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.
Re:my first audio cds are dying (Score:3, Informative)
Re:Another 6 months, another CD longevity article (Score:2, Informative)
For the google impaired [bbc.co.uk]
BTW it was the first link when I searched for CD eating fungus.
Re:FUD (Score:1, Informative)
Verbatim are the only blank CD's I have found which I can trust to burn at full speed without making coasters. I can buy a pack of Memorex or other midrange brand; Im sure that if i were to burn at full speed out of a pack of ten i'd get one or two coasters. I've never ever had a verbatim bum out on me.
Okay my comment was a bit of a sweeping generalisation but generally speaking I have found that quite often in life opting for the cheaper alternative usually means you'll end up paying for a replacement in the future. In the long run you'll end up paying more, as cheap things fail more easily requiring replacement.
nick
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.
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.
DVD-R Longevity (Score:1, Informative)
There is a company [weddingdvd-r.com] that has come out with long-life silkscreened "Our Wedding" DVD-Rs just to make sure that your $3000 wedding video doesn't evaporate on your 5th anniversary.
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.
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)
Re:my first audio cds are dying (Score:3, Informative)
So maybe you've gotten so used to the sterility of digitally-mastered CDs that your old Hendrix CDs sound like LPs by comparison.
Re:Eternal archiving. (Score:2, Informative)
Re:NIST Study (Score:5, Informative)
Re:This bugs me. (Score:3, Informative)
RAID 5 is the way I'd go if I could afford it. If a drive goes down, you can replace it. This works well if you need constant access to the files.
For archival needs only, I usually just make 2 copies of CD-r's. Of course now I use Princo DVD-R's.
To be even more secure, you could make PAR files. That way if any individual files are bad, you can recreate from the PAR files. If the collection is big enough that spans many CD/DVD-r's, you can even have enough pars to recreate a WHOLE disc that went bad. Unfortunately, of course, if the medium is suspect... then obviously the PAR files are also vulnerable. Basically PAR files would only increase your chances of recovery based only on partial errors.
And last but not least, put everything on a new hard drive, and pull it. Put it on the shelf. This illiminates almost all wear-and-tear, and you only have to worry about hard drive decomposition. (Which I believe is not really a big scare nowadays) You can even buy those Hard drive bracket/rack thingys so that you can cold-swap in and out of your case with ease.
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].
Re:Longevity of analog content vs. digital content (Score:2, Informative)
The word "media" is plural; in the singular form it is "medium". The error of using "media" as a singular is extremely common in the computer world, but it's an error.
Sorry for being a pedant. Otherwise, brilliant point by debest.
Suspect (Score:2, Informative)
The studies that are linked are very suspect... The linked articles mention that they use ordinary, off-the-shelf CD-ROMs. The Library of Congress study is skewed because all samples were for CDs manufactured before 1997. This is like studying current car safety by grabbing some old Corvairs out of a junkyard. (Were the CDs commercial-quality or archival-quality?)
Well, I know that hospitals use more expensive, archival-quality CD+Rs. I wonder how the results would change if they used CD+Rs like these:
Medical CD+Rs [mitsuicdr.com]
Archive CD+Rs [mitsuicdr.com]
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.
100 years? Can be done! (Score:3, Informative)
Edison cyliders have lasted 100 years (with proper care), shellac 78's and magnetophon recordings have lasted 70 years (with proper care), reel-to-reel recordings have lasted 40 years (with proper care), and I suspect that CDs will last a long time - with proper care. Commercial CDs are nowhere near as resiliant as the inital marketing told us (who ever doubts marketing?), burned CDs substantially less so.
So, for those who STILL haven't a clue on CD care, here it is again:
1) Choose a CD that sandwiches that data layer between two polycarbonate sheets, rather than ones that have the data layer printed on (I'm looking at you, TDK). Make sure the rim of the disk is sealed with varnish (you can tell by looking closely);
2) Keep away from light (of any kind). I know geeks don't get out much, but leaving anything in the sun is bad, and the polycarb in CDs is NOT UV stable, nor is the chemistry in the data layer (if it was that chemically stable, you wouldn't be able to burn it, would you? Think about it...);
3) Store them somewhere not subject to large temerature variations (an old fire safe is good for this. I've said this before in other posts, but people got the wrong idea: a fire safe will not protect CDs from fire! It is simply a large, heavy, thermally stable box. Sure, you could use a cupboard in your basement, but most basements are not very dry, which brings up the next point);
4) Keep 'em away from moisture & humidity. Don't throw out all those old silica gel packs, they're ideal. Tupperware is a good investment for archiving;
5) Labels? Hmm, lets see, take a piece of paper covered with volatile solvents, and place it against your data layer. Anyone with half a brain could see that it was never a good idea (I've never labeled CDs with anything other than Xylene-free markers - not neat, but who cares what the CD looks like, I want my data intact). Labels, improperly positioned can cause imbalances in a CD which can make it unreadable, and gloss labels can cause CDs to become stuck in slot-load drives (iMac owner speaking from experience here, but it applies to car stereos too);
6) Never, EVER, use CD-RW for permanent backups. They are less stable than CD-R, naturally. Use some logic, folks: if CD-RW were more stable that CD-R, it would be easier to erase a CD-R than a CD-RW, wouldn't it? Its more complicated in reality, but that sums it up in a nutshell (and I've already exceeded the attention span of most
The down side of any digital medium is that in order to recover the data, you have to read ALL the 1's and 0's (or at least a good percentage of them, given reasonable error correction). Analog storage at least has the advantage that even a degraded signal is recoverable and intelligable, at least for speech applications. So while a cassette might be readable for much longer, it will start having problems like print-through, particle shedding and substrate stretch from day 1.
No medium will last long if it isn't well cared for. Its as simple as that, but unfortunately some people are even more simple.
Re:Pressed vs DIY (Score:1, Informative)
Re:Writing speed (Score:3, Informative)
I have to agree with unothod0x. I have a Lite-On 48x24x48 CD-RW drive. If I burn any CD-R (tried using Memorex, Sony, and Maxell rated 24x up to 48x) at any speed higher than 4x my car CD player will not recognize the disk at all. At speeds of 4x or lower there seems to be no difference on that player. On my home stereo system, the CD player can read disks burned up to 12x, with some skipping, no skipping if burned at 4x or below. My APEX DVD player will only recognize VCDs burned at 8x or less. YMMV
Re:CD Rot (Score:2, Informative)
I'll never use them again.
Re:MAM-A "gold" metallized layer is aluminum not g (Score:5, Informative)
Copying r2r to cassette is like copying to playdoh (Score:3, Informative)
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:NIST Study (Score:4, Informative)
Re:Nonsense! (Score:2, Informative)
For non unix users, dd can be used to copy a file bit for bit. Since Everything Is a File, you can copy a file to a harddrive without using a filesystem.
Comment removed (Score:2, Informative)
Re:Nonsense! (Score:3, Informative)
Beyond this, you have to worry about redundant acccess to the data at the same location (drives are OK, but system board dies), and redundant data in case of catastrophic loss such as natural disaster or terrorist attach. In the first case you would probably cluster, and in the latter case you would perform some sort of mirroring. If you are further serious about this, you of course have redundant data lines between locations (of multiple types - satellite, some T1s, DSL, etc) so you can guarantee the mirroring, and you cluster at each location.
Of course, none of the above will guarantee your data survives a comet strike, but perhaps someone will begin vaulting services on the bright side of the moon just in case.
Re:NIST Study (Score:2, Informative)
2. Use a non solvent-based felt-tip permanent marker to mark the label side of the disc.
Last I checked, alcohol is a pretty damn good solvent... Oh yeah, water is too, actually...
Oil? Not so much, although it may degrade the surface of the media in other ways.
Early CD experiences (Score:3, Informative)
On some there was an oily creamy layer on the bottom side. On others there were lots of needle thin holes in the disk - you could actually see light through. Still others had the different layers separating, with water in between [...] We've seen the phenomenon in the very first generation of CDs from the early 80ies. In a box of 50 CDs from the same year there were maybe two dissolving, so lifetime must depend on manufacturer and material
Re:Nonsense! (Score:3, Informative)