Slashdot Mirror
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."
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.
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.
The story about the Rot of Death seems to come up every once and a while. My fun strategies for longevity:
- 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.
Auto-reply to ACs: "Truly, you have a dizzying intellect."
The 100 year CD-ROM becomes a 27 million year CD-ROM, and they plan to have their copyrights extended that far.
Store them on a series of floppy diskettes. They have proven to be VERY reliable. ;)
Ever decreasing circles
Factor that in with the project the BBC did in the mid-1980s (A digital Domesday book, designed to be a snapshot of life at that particular moment of time) that was unreadable withing 20 years because of the fast pace of technology and no way will CDs last 100 years.
HAH! I just wasted a second of your life making you read this, but I wasted a minute of mine thinking it up. DAMN.
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.
Rename the MP3s of your grandfather's voice to coors_twins_baby_oil.mpg and put it on Kazaa.
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.
3D Printing Tips and Tricks at Zheng3.com
I know lots of people that have "worn out" cd's. The first time I heard that, I thought they were kidding, but no... even if you take super great care of say, an audio cd, it will eventually wear out. It's especially bad if you keep it in the original plastic jewel case, and take it out each time -- my friend's rare Pearl Jam CD's are nearly scratched beyond playability, but he was able to extract the digital information before it got lost. What makes CD's better than tapes is that the 0's and 1's will always "be the same" logically, unfortunately the physical media wears out quickly with use. I prefer to think of CD's as a temporary storage mechanism for a permanent idea, like a sketch on newsprint. Once the newsprint disintegrates, you'd better hope you made something good with the idea... it doesn't mean the idea is gone, but the medium isn't like stone.
stuff |
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.
It's not exactly a fair comparison between CD-R and analog tape for audio. The audio tape isn't "more reliable." It just degrades differently.
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.
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).
Keep original copies on the Harddrive, Cassette, ect and then make copies as needed.
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
Work Safe Porn
I have found most of my cdr's that are that age or older are starting to fail.
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?
---- Booth was a patriot ----
The first link is to rense.com, a website that promulgates the theory that the US government is experimenting on us with "chem trails" emitted by otherwise innocuous-looking aircraft flying overhead. The webmaster at that site obviously has a very low threshold for rubbish, and no critical thinking ability!
What's the deal? This same article with a slightly different look shows up every 6 months, it seems.
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.
Some of my first cds purchased in 86 (Are You Experienced and Electric Ladyland) are clearly losing sound quality.
love is just extroverted narcissism
I don't get this obsession with hoping to keep media for 100 years. Technically punch cards are forever. Do you still use them ? No, because their storage capacity is ridiculous by today's standard. In five years you will store your data probably on your solid-state 200 g key-chain.... move with the times..
All this about CD's not lasting very long is just FUD by the RIAA. In the next few years or so they will want to bring out a new type of media so that everybody has to restock their cd collection with the new media format.
...
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
Electronic Music Made Using Linux http://soundcloud.com/polyp
The BBC Library still uses vinyl records for long term audio storage. For some items they cut a lacquer master, plate the metal stampers on the lacquer and leave the metal stampers attached to the lacquer.
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.
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.
Dewey, what part of this looks like authorities should be involved?
...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.
My Greasemonkey scripts for Digg &
Now, you can enjoy your CDs for a long time...
It's a small world and it smells funny; I'd buy another if it wasn't for the money; Take back what I paid (SoM)
Anybody want to fund me? :) Is somebody already doing this? I might be interested, I've got files I've been kicking around for almost a decade that I'd hate to loose.
The meek shall inherit the earth, in 3 by 6 plots. - Lazerus Long
Personnaly I just discovered 6 audio cassettes with the voice of my late grandfather.....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
Go ahead and digitize everything. Then get yourself a couple of accounts at Gmail 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 and Ben Gay, but nothing is perfect.
Take the cheese to sickbay, the doctor should see it as soon as possible - B'Elanna Torres, "Learning Curve"
It's all well and good to have a CD to back up your precious files (Audio, Video, documents etc) to but this doesn't cut it as a real backup.
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
I'm sure what I'll say has already been said, but I can certainly attest to the shorter-than-advertised longevity of CDR media. I recently had to pull some long lost files off of CD's I burned back in the college days, probably 5 years ago or so. These consisted of several types of media, both cheap and expensive, green and blue dye, sticker and no sticker. Basically the dye color has little effect, and stickers really do call for the early death of the media. But most of all, I think it was the early CD burning software or the actual CD-Rec drive that I used. Some earlier CD's, that I know I burned at work (using the latest software at the time) were near flawless. But a batch burned later, on a friend's computer using some lesser known software, was completely corrupt (TOC and CRC errors abound). I now make sure I get decent CDR's like TDK's (not the cheap CompUSA stuff), don't use stickers, always keep them in a multi-CD case, and run a bit-for-bit check on the archive after burning with Nero. I have yet to have a problem since I started this practice at least 2 years ago...although time will certainly tell.
Sometimes I doubt your commitment to Sparkle Motion.
I now write myself a little note on my CDRs to indicate how much of the surface causes read errors. Nero's "CD Speed" tool is very useful for this, as it has a ScanDisc tool incorporated within it.
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.
Although it seems like burning at a slower speed means that your data lasts longer, for some newer CDs burning at 2x might actually cause your data to be less secure. Most CDs sold nowadays are optimized for faster burns, say at 48x. The "fast" media doesn't handle slow burn speeds quite as well as older media optimized for 2x would.
convert everything to mp3, and send them to your gmail account, they will be kept here forever in multiple redundant copies
"Science will win because it works." - Stephen Hawking
The article says Not all optical media is vulnerable. The rewritable variants (RW) use metallic materials that change the phase of the light, rather than light-sensitive dyes. Commercial magneto-optical and ultra-density optical systems are different too. Do they mean to say that CD RW's are resistant to aging compared to CD-Rs ??
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's why I bought the Unreal Tournament 2004 Special Punchcard Edition.
a /U T04-PunchCard.gif
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!
So i guess someone was paying attention in Stats class ;)
That does it. I'm converting all my mp3 collection to 8-track tapes. Does anyone know of a good 8-track tape recorder that mounts in a typical tower 5.25" drive bay to make this easy?
Don't blame Durga. I voted for Centauri.
"Real men don't use backups, they post their stuff on a public ftp server and let the rest of the world make copies." - Linus Torvalds
I think you are doing the right thing. Who has time to dick around backing up to CDs, tapes, etc? To me, any backup solution that spans multiple tapes, etc is severely broken.
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.
slashsearch.org - slashdot search. powered by google.
The National Institute of Standards and Technology also has an extensive guide, Care and Handling Guide for the Preservation of CDs and DVDs, including a one-page Do-and-Don't Quick Reference.
On a related note, I recently recovered all of the contents off of the lone C-64 5.25 in floppy that I saved from my junior high/high school days of the late 80's. The disk had been sitting in between the pages of a programming book for around 15 years.
... no wonder I'm an emacs freak!
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
When I buy a cd in the store, I expect professional, archive quality CDs. If I've got to burn off the music myself (and can only do that a limited # of times) I've got to use my cheap 'ol cds. I guess most music services would track you're licences and let you download them again (provided you're computer hasn't changed, God I hate DRM). Still, at 99 cents/song with only shaky garuantees I can access the song perpetually, it seems like a raw deal.
Hi! I make Firefox Plug-ins. Check 'em out @ https://addons.mozilla.org/en-US/firefox/addon/youtube-mp3-podcaster/
Analog methods of storage (such as good old paper*) will pretty much always be able to outlast any method we have to digitally store information, at least for each "generation" of copies that are required.
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.
Look at the tomato! Isn't it sad? He can't dance! Poor tomato!
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.
... if you know what you're doing. First of all, there are specialty CD-Rs intended for archival purposes. These will inherently last longer than normal CDs for numerous reasons, assuming the manufacturers are not full of crap. To find these CD-Rs, check a photography store, as photographers tend to have a need for both archival and mass storage thanks to digital cameras. You will likely find some there.
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.
Random and weird software I've written.
The best is Mitsui Gold.
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.
Really, what do you expect when most people pick up spindles that all some from the crappy Ritek or Princo plants in Taiwan because they can get them for $9 a spindle? I've had those go blank on my shelf too, and now I know better.
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.
Many people seem to suggest reburning data every few years. But each time you do this, are you not risking corrupting a small number of files? I know OSs and hardware have error correction, but when you're dealing with gigabytes of data isn't there a risk that eventually an error will go through uncaught?
One Terrabyte actually, for about $1199.
Yes, I can imagine a Beowulf cluster of these...
A message from our sponsor
The ONLY brand of CD-ROMs that I've found to last a long time are the Kodak ULTIMA series. Sadly, Kodak has stopped producing these CD-ROMs. I have several that I burned back in 1994-5 and they all still read with no errors.
I wish Kodak would bring these CD-ROMs back into production; I'd even be willing to pay a premium for them. When it comes to archiving data or something precious (like your late-grandfather's voice or late-mother's audio diary), cost really isn't an object. What's important is protection and preservation of history (in a sense).
If "disco" means "I learn" in Latin, does "discothèque" mean "I learn technology"?
pronoblem
I have about 50 CDs that are 10 or more years old? What are these people doing, storing their CDs in Coca Cola?
CD-RW disks will last longer than CD-R because of the way it stores it's bits.
CD-R uses a dye that changes color under influence of light. CD-RW uses a phase change material that changes it's properties because of heat. The phase change material won't change color but changes the way light passes through it. Differences in the duration of the laser hitting it will change a bit from one phase to another.
CD-RW disc information is much safer because of these differences. The only problem with CD-RW is that you can accidentally overwrite files you wanted to keep.
- -- Truth addict for life.
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.
Why are there only 19 people folding@home for slashdot?
(2004/02/17) in CD-Recordable FAQ:
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/) on http://www.informationweek.com/story/showArticle.j html?articleID=15800263&pgno=1
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,
especially http://www.cd-info.com/CDIC/Industry/news/media-ch ronology.html 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.
Ant(Dude) @ Quality Foraged Links (AQFL.net) & The Ant Farm (antfarm.ma.cx / antfarm.home.dhs.org).
The number of things that can go wrong with old magnetic media is so long I won't even go there. If nothign else, the magnetic tape will get old and brittle. It also stretches slightly when you play it, which could leave granddad sounding like James Earl Jones in a few years. Certain types of mildew love it. AAAAAA! Make a copy! Make a copy!
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.
ad logicam Claiming a proposition is false because it was presented as the conclusion of a fallacious argument.
I have, since 1984, written all my school papers, letters to friends, etc., on a computer, starting with WordStar 3.3. I thought I had a foolproof method of preserving them...every time I got a new machine, I just copied all the documents over to the new machine (first using laplink cables, later ethernet). Now, 20 years(!) later, I have my documents on my shiny new dual G5. And guess what! I can read maybe a 4th of them as no program understands the WS format, later WP4, WP5, etc. etc. Sure I have all the documents, but the all I can show off to my grandkids is a random collection of bytes that was "Why are oceans necessary?" from 1984.
But it doesn't end there...people talk about magnetic tape as being a viable medium; I have plenty of tapes that don't play right because they were recorded with a different speed recorder than what is available today. My little piano recital sounds like a Keystone Kops tune on acid.
And how about all those betamax tapes I've got of me playing tackle football when I was 11 years old? Still got 'em. Wish I still had a Betamax to play 'em on.
And then, I have a bajillion slides, taken by me and my family, on Kodachrome25. Stuff lasts forever. They've faded a bit, but I can still view them if I hold them up to the light. Wish I could show 'em to my grandkids but I don't have a slide projector. I suppose I could scan them into the computer......
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
Archive CD+Rs
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.
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.
AFAICT, reading all the available literature from Mitsui on their gold MAM-A discs, the reflective metallized layer _is not actually gold_. It's aluminum.
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.
Just digitally remaster it, then record it on the best analog you can find. You get most of the quality, and all the durability...all you lose is the convenience, really.
How long a medium lasts is related to how well its cared for. I've seen cassettes that have lasted 30 years, but I've also seen 2 Inch multitrack tape (eg Ampex 499, around $300 for a 15-minute reel) become totally unusable after 10 years.
/.'ers)
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.
Umm... what literature would that be? There is a white paper which explicitly states that the reflective later is 24k gold.
So what if a CD doesn't last a hundred years? It's still a digital medium, which means that as long as there is one good copy, you can make an unlimited number of exact duplicates with no degradation in quality.
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.
Punctanym: alternate spelling of words using punctuation or numerals in place of some or all of its letters; see 'leet'
Real men write stuff that the rest of the world wants to copy.
Cassette is the WORST FORMAT EVER RELEASED. It is the lowest quality, and the most error prone, even more error prone than r2r AND the fidelity is terrible. If you HAVE r2r then dear god, copy it to some high end format, not cassette.
ad logicam Claiming a proposition is false because it was presented as the conclusion of a fallacious argument.
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.
We burn about 200K CD-R's here per month. We have found, unequivocally, that you can burn data CD-R's at 40x, but the best we can do for audio is 12x. We don't really know why, but we think it has more to do with the error correction capabilities that the data format has. That's the theory, anyway. Of course, we use only the best drives and media.
No, the cassette was just changing to reflect the current Jackson.
The only reason we have the rights we have is that people just like us died to gain those rights. -- Cheerio Boy
We all know that clay, stone, and ceramic records can last for thousands of years in terrible conditions, but those records are kilo-bit order projects, and an entirely different animal than sound.
One thing this guy may want to consider is a Rosetta type of storage system. If you convert the reel-to-reel recording to a digital format, then transcode to a uuencode style format, the result could be recorded in an extremely stable human and machine readable format.
If the guy really wanted stability and long term interpretability, he could encode a 1Khz sine wave using the same method and use that as descriptive meta-data. That way future generations could have nice, simple test file to run their automated decoders on. Even if all knowledge about how the file was encoded is lost, the repetitie pattern would probably be noticed. If the archivists in 2152, common era, have any idea that the disk is a sound recording, they'll surely figure the rest out.
I work with a amateur historian that's quite looney, over all, but she is always making good points about meta-data. Recording information about the sound, how it was made, who made it, and anything you can think of might make the difference between a sad lost opportunity and a major discovery. Historian types really love it when they find an old picture with names and dates written on the back. Often they can use their other archives to cross reference and to infer information that would be impossible without the meta-data. For example, they could use a known good picture of a certain building, and a picture of a person with a part of said building to place that person in a certain town at a certain time. That's a small example, but anyone can see how important a small point can be when trying to figure out a puzzle with 90% of the pieces destroyed.
Also, the guy may want to think about getting the originals into proper storage. That may mean giving them to an institution, but it beats having them destroyed because your cat peed on them.
People are spending big bucks to recover wax cylinder recordings of opera singers. Surely they'll do it for actual historical records put down by eye witnesses!
This guys sounds interested enough to re-record every 5 years to the latest and greatest storage technology, but what about his heirs? If fate curses him with Alzheimer's disease, will his kiddies care of have enough energy to do the job? Probably not and the chain could be broken. That's the real threat, I think.
Why do I have this? I don't smoke.
Clay Tablets, they seem to have the best proven track record for data as a whole. Of course, if you have the money, you can always use a norsam disk, they may last even longer than clay- but I doubt they're cheaper. Of course, for large amounts of data, storage is a problem.
Seriously, there should be a digital->clay device, like a printer or something, for super-archival 4000 year proven quality at a bargain. I have thought about making one for a while- a sort of dot-matrix for clay. I think it would be fun!
I think it depends on what information one considers important. The more different information you have, the less durable each corpuscle of it is. The more identical, permanent, memorable information you have, the more durable it will be. Of course, I think it would be difficult to put audio on a clay tablets, but not lyrics. We have the songs to Inanna by Enheduanna even today- that's some star power.
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.
The society for a thought-free internet welcomes you.
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!
I just check some specs from www.kingston.com and the data retention for their flash memory (CF, USB drive) is only 10 years.
Tape seems to tolerate degradation better because if a few magnatic "bits" flip, it won't make much difference, mostly just more background hiss. However, if a digital stream loses a bit or two, the current algorithms cannot recover very well.
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.
Table-ized A.I.
I was one of the original developers for Magneto Optic for MaxOptics and Pinnacle Micro Systems approx 20 years ago. I still have media recorded back then on truly rewritable optical media that is 100% flawless to this day. And all this is on Plastic Media. I never did understand why magneto optic didn't catch on more. The Glass Media units I'm sure would go to 100+ years and were tested in Europe for the telephone and data companys 20 years ago, and the last I heard they still hadn't seen a single cartridge with glass media go bad.
Ah, I'll answer my own question.
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.
"Those who have never entered upon scientific pursuits know not a tithe of the poetry by which they are surrounded."
For the record, here's what the Council on Library and Information Resources says (emphasis mine):
Is this just theory or does it really happen? Does anybody have a CD or DVD that became warped because of storing it horizontally? Almost all disc storage towers and cases hold them horizontally.Comment removed based on user account deletion
You think that's something to have a recording from 1971? I've got hours and hours of tape from a group of guys in 1963 through 1967; it doesn't just have their voices but they sing, too! Songs about advice with girls (She Loves Me, I Want to Hold Your Hand, Baby You Can Drive My Car, Hey, Jude), recreational drugs (Lucy in the Sky with Diamonds, Strawberry Fields), politics (everything else, basically). And my aged dad, now a granddad himself, has tapes and "LPs" (larger than a CD but with better quality audio; infinite bits, ya know) of dudes from the 1940s and 1950s! Whoo!
Damn kids. 1971 is a benchmark for longevity?
-- @rjamestaylor on Ello
The nat'l library of Denmark is now copying CDs (pressed, not burned) that they archived in mid/early 80ies. They have an archive of 25'000 CDs - never played, never exposed to light or heat. Just last week an article (danish sorry) about it. Select quotes:
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
Any sufficiently advanced libertarian utopia is indistinguishable from government.
Reminds me of that poem by Percy Bysshe Shelley:
I met a traveller from an antique land,
Who said -- "Two vast and trunkless legs of stone
Stand in the desert... Near them, on the sand,
Half sunk a shattered visage lies, whose frown,
And wrinkled lip, and sneer of cold command,
Tell that its sculptor well those passions read
Which yet survive, stamped on these lifeless things
The hand that mocked them, and the heart that fed;
And on the pedestal, these words appear:
My name is Ozymandias, King of Kings,
Look on my Works, ye Mighty and despair!
Nothing beside remains. Round the decay
Of that colossal Wreck, boundless and bare
The lone and level sands stretch far away."
That's probably because CD writers use CAV (constant angular velocity) for writing speeds above 12x. CDs were originally developed to use CLV (constant linear velocity), meaning that the rotation speed slows down as the head goes toward the outer edge of the disc--if you have an older CD player that lets you see the spindle or CD while it's spinning you can verify this (it's easiest to see when the head is seeking from one edge to the other). I'm not an expert in CD technology, but I've had similar results using discs burned at 12x vs. 24x on a 24x writer--the 12x discs work better in older players and CD-ROM drives--and I suspect it's because of differences in the way the disc is written between CAV and CLV.
If I'm talking out of my ass, I'm sure someone will correct me . . .
It is normal, and to be hoped for. Retaining historical knowledge doesn't cause us to stagnate. It gives us a base to build off. Can you imagine if every school year you had to start over because you didn't retain the information from the previous year? An extreme example, but I think it gets the point across. You stagnate when theres no growth, and there cant be growth if theres no history to grow from. Whether its printed media, or digital, the concepts the same.
...about 5 years ago. it bombed. there was also the superdisk. it bombed. now we have usb flashdrives with generic USB bulk storage drivers.
they may not be any longer lasting though - the only answer is archive and periodically read and rearchive to the latest storage medium.