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TECH: How long do CDRs last?

GUEST,Will Parkins 01 May 02 - 01:53 PM
MMario 01 May 02 - 01:55 PM
GUEST,Will 01 May 02 - 02:09 PM
MMario 01 May 02 - 02:14 PM
JohnInKansas 01 May 02 - 02:18 PM
GUEST,Will 01 May 02 - 02:42 PM
MMario 01 May 02 - 02:52 PM
GUEST,.gargoyle 02 May 02 - 01:44 AM
Ralphie 02 May 02 - 02:48 AM
Ralphie 02 May 02 - 02:55 AM
JohnInKansas 02 May 02 - 06:48 AM
mack/misophist 02 May 02 - 09:25 AM
Lonesome Gillette 02 May 02 - 09:55 AM
JohnInKansas 02 May 02 - 10:07 AM
treewind 02 May 02 - 10:29 AM
JohnInKansas 02 May 02 - 11:07 AM
English Jon 02 May 02 - 11:24 AM
Devilmaster 03 May 02 - 11:16 AM
JohnInKansas 11 Aug 02 - 11:14 PM
NicoleC 11 Aug 02 - 11:56 PM
GUEST,misophist 12 Aug 02 - 10:14 AM
treewind 12 Aug 02 - 10:37 AM
Mr Red 12 Aug 02 - 11:02 AM
NicoleC 12 Aug 02 - 12:42 PM
Mr Red 12 Aug 02 - 06:10 PM
GUEST,JTT 12 Aug 02 - 06:35 PM
johnross 12 Aug 02 - 11:23 PM
delphinium 13 Aug 02 - 01:00 AM
GUEST,Mr Red at library 14 Aug 02 - 08:38 AM
John J 15 Aug 02 - 08:59 AM
Mr Red 15 Aug 02 - 10:27 AM
GUEST,JTT 15 Aug 02 - 10:29 AM
Bill D 15 Aug 02 - 10:34 AM
treewind 15 Aug 02 - 10:46 AM
robomatic 15 Aug 02 - 12:58 PM
GUEST,steve.peach@ntlworld.com 15 Aug 02 - 04:47 PM
Mr Red 15 Aug 02 - 07:38 PM
GUEST,Mark Ross on the road 16 Aug 02 - 01:42 AM
JohnInKansas 16 Aug 02 - 04:41 AM
GUEST,Gurney 16 Aug 02 - 06:50 AM
mack/misophist 02 Sep 03 - 09:50 AM
WFDU - Ron Olesko 02 Sep 03 - 10:09 AM
mack/misophist 02 Sep 03 - 01:59 PM
WFDU - Ron Olesko 02 Sep 03 - 02:09 PM
mack/misophist 02 Sep 03 - 05:42 PM
GUEST,WarDog 27 Oct 03 - 02:38 PM
Burke 28 Oct 03 - 12:26 PM
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Subject: TECH: How long do CDRs last?
From: GUEST,Will Parkins
Date: 01 May 02 - 01:53 PM

How long can you expect a home-burned CD to last?

I've got a couple from about 3 years ago (one software, one music) which are now unusable.

Is that normal?

Thanks for any thoughts, or ideas for better archiving solutions.

Will


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Subject: RE: TECH: How long do CDRs last?
From: MMario
Date: 01 May 02 - 01:55 PM

How are they stored? CD-R media is more liable to corruption thorugh sunlight and temperature changes than are commercial CD's


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Subject: RE: TECH: How long do CDRs last?
From: GUEST,Will
Date: 01 May 02 - 02:09 PM

Mmario,

Both of the knackered CDs were generally stored in their cases, in a draw, in my house.

Certainly not in direct sunlight or with any massive temperature changes.

Dying after 3 years seems dreadful (and I'm tried them in several machines).

Maybe the technology has moved on in the last few years, but I'm going to be wary of archiving anything long term in this way, until I know better.

Will


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Subject: RE: TECH: How long do CDRs last?
From: MMario
Date: 01 May 02 - 02:14 PM

Estimated usable Life span as far as I can find is in the hundreds of years.

Floppy;tape; zipdisk and superdisk can both all fail within three years - what other medium would you suggest?


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Subject: RE: TECH: How long do CDRs last?
From: JohnInKansas
Date: 01 May 02 - 02:18 PM

I've been looking for some believable info on this for a while now, with no particular success. It appears that "commercial" CDs are generally "pressed," so that the pits that contain the information are actually embedded into the parent material of the disk.

The laser used in CD-R recorders is relatively low-powered, so a more "delicate" recording layer is "pasted onto" the disk. Since the actual recording material is a separate part, deliberately made "vulnerable" to modification by the low-watt laser, it must certainly be more fragile than a single chunk of plastic.

Instructions with higher quality data CD-R disks warn against even placing labels on them, aparently because any damage to the "shiny side" can cause loss of data. I've certainly noted that even apparently minor scratches - that wouldn't do much damage to a "pressed" CD, will make a CD-R unreadable; and that the CD-R back surface is much more easily scratched.

John


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Subject: RE: TECH: How long do CDRs last?
From: GUEST,Will
Date: 01 May 02 - 02:42 PM

what other medium would you suggest?

Mmario,

I don't know! That's why I started the thread...

Will


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Subject: RE: TECH: How long do CDRs last?
From: MMario
Date: 01 May 02 - 02:52 PM

As far as I know - there is no cheap, reliable LONGTERM means to backup. All solutions I have seen to be effective rely on routine examination and multiple duplication of the archived material. Usually the material is also reprocuced at intervals - as seeds are taken out of a seed bank and a generation or two are raised and harvested to ensure viability of seed.


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Subject: RE: TECH: How long do CDRs last?
From: GUEST,.gargoyle
Date: 02 May 02 - 01:44 AM

An old-time axiom is - You get what you pay for

My experience (with over four hundred R cd's) is that the "gold" last forever (one dollar US apiece) ....and the thin silver (ten cents on sale, sometimes free with rebate) are good for seven to ten plays.

This is burning at 2X with Yamaha, Hitachi, and HP burners.

Sincerely,
Gargoyle


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Subject: RE: TECH: How long do CDRs last?
From: Ralphie
Date: 02 May 02 - 02:48 AM


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Subject: RE: TECH: How long do CDRs last?
From: Ralphie
Date: 02 May 02 - 02:55 AM

Woops...Posted before writing!! Sorry!
As has been said already, CDRs are are photographic medium, and, therefore very susceptible to Heat/Light...As the technology is only a few years old, I don't think that anyone can say with any confidence how long they will last....I use DATs a lot for work, and have some that are over a decade old, but, who knows in the future. I've transferred some of my tape archive to DAT and CDR for ease of playing....But, I've still kept the tapes....!!
Memo to self...Must buy bigger house!
Regards Ralphie


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Subject: RE: TECH: How long do CDRs last?
From: JohnInKansas
Date: 02 May 02 - 06:48 AM

A previous thread How Long Do CDs Last might be of interest.

I would point out that I, at least, and possibly some others, did not realize the need to distinguish between "commercial" and "home-brew" CDs in that discussion.

The commercial "pressed" CD has the surface of the "groove" shaped to change which way the light bounces during a read operation. Scratches on the "data" side that do not go to the bottom of the groove may have relatively little effect on whether you can read the disk. And since it's the gross shape of the material that stores the data, the CD is very resistant to degradation.

In addition, the "reflector" on the back side of the disk is relatively non-critical, as long as it bounces back a fair share of the light that hits it.

Some time back, there was talk of at least two competing methods for "home-recorded" CDs. In one, the "crystallization" of the plastic adjacent to the reflector is modified by the writer, so that it "deflects" the read beam. In the second method, "pits" are actually "smudged" into the reflective coating on the back of the disk. I have been unable to find any current information on the "physics" of the home brew burners, so I don't know for sure which of these (or other) methods are commonly used. Either of these methods, however, depends very critically on the back reflector being "near perfect." Particularly where the reflective coating itself has to be affected by the write laser, it must be made fragile, or the writer wouldn't be able to do anything to it.

So far as I know, NO HOME CD BURNER has a laser of sufficient power to actually "burn" anything. (In my country, the "laws of OSHA" don't permit it.) The most it can do is "tweak" something. In order for the low power burner to have an effect, the "thing that is modified" must be, literally, unstable, and hence not a good candidate for long term stability after the recording is made - since any outside influence approaching the original writing power can, potentially, upset the change made during writing.

The "hype" that says we can "burn our own CDs just like the big boys" is sales talk. We can store large amounts of data, but the device we must use (the CD-R) is NOT the same animal as the commercial "pressed" CD.

John


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Subject: RE: TECH: How long do CDRs last?
From: mack/misophist
Date: 02 May 02 - 09:25 AM

John is correct. My instructors all say that, under the best conditions, a cd-r won't last over 5 years.


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Subject: RE: TECH: How long do CDRs last?
From: Lonesome Gillette
Date: 02 May 02 - 09:55 AM

wow. glad I read this.
Lots of my daughter's baby pictures are saved on CD. I assumed they were good to go for a million years.


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Subject: RE: TECH: How long do CDRs last?
From: JohnInKansas
Date: 02 May 02 - 10:07 AM

Lonesome G

It's my understanding that some commercial processors actually use CD "burners" to archive photos to order - as opposed to the common CD "writers" most of us have. If they're on "industrial grade" CDs, your photos should have fairly long life.

Probably, if you wrote your photo CDs yourself, on CD-Rs, you can't really consider them "archived."

I've just begun to discover bits and pieces about this, and hard data is very difficult to find - so far.

John


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Subject: RE: TECH: How long do CDRs last?
From: treewind
Date: 02 May 02 - 10:29 AM

There is some more and possibly the most reliabe and up to date information on the CD-Recordable FAQ web pages.

The ability to keep the data does not depend on the power of the CDR recorder's laser. The CDR preamble (data already burnt in at the start of the groove) actually indicates a recommended writing power, which depends on the dye used and manufacturing process, and the recorder (if it's nay good at all) adjusts itself as directed. Too much would fail just as badly as too little.

Anahata

P.S. here's some of the CDR FAQ on this subject:

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.

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.


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Subject: RE: TECH: How long do CDRs last?
From: JohnInKansas
Date: 02 May 02 - 11:07 AM

treewind -

Looks like a good site - I'll get further into it later. As a user-group FAQ though, it still just skims the surface with "somebody's opinions." Hopefully there may be some leads to some physical data there.

The "plastic" used as the base for the disks in either type, CD or CD-R, should be fairly stable, although it would be necessary to know fairly precise formulations for the materials to guess about the basic dimensional stability of the material. IF the data is written as dimensional changes to a surface, you've got a "mechanical device" that should last a long time under good storage conditions.

The reflector that is bonded onto the back of the disk is also critical. The metal itself, any bonding agent used, and any crystallographic stresses produced either by bonding or by the recording process may affect how long the disk is "stable."

If the data is written by changing the crystallization of the plastic, then self-annealing will occur, and the data will change. Rates can be predicted for some material combinations; but again, it is necessary to know the precise material combinations and what changes are made in recording the data.

If the data is written by "burning" or "smudging" the reflector, then you need to know whether this affects the bond between disk and reflector, as well as the crytallographic properties of both parts, in order to make any reliably guesses.

Unfortunately, most of what I'd like to know about these things is probably considered "proprietary" by the disk and drive manufacturers, and they're not making it available.

Suffice to say that "I've had it with ZIP drives" - too many disk failures. Floppies simply don't provide enough storage space to be useful. I've tried tape: backup is easy, but I've never gotten a fully successful restore of anything of significant size.

At the present time, the CD-R is the method of choice for data storage off the hard drive. I would not however recommend that anyone treat the longevity of CD-Rs as a "given" in any "archival" situation. (That's an IMNSHO, of course). Data maintenance is still needed.

John


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Subject: RE: TECH: How long do CDRs last?
From: English Jon
Date: 02 May 02 - 11:24 AM

Guy at hampshire record office says that you can expect three years, maybe more if you store in dry conditions, cooler the better. Watch out for paper cases. Acid in the paper eats the discs. Removable HD isn't much better. Not really designed for archiving. Best bet is to load up any important CDRs once a year and burn new copies.

EJ


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Subject: RE: TECH: How long do CDRs last?
From: Devilmaster
Date: 03 May 02 - 11:16 AM

Just a thought out loud.

Guest Will had said 3 years on those disks. My first burner was an early one, 2X Memorex. It really never burnt a good copy of anything. And to ensure the best possible burn, I needed to use it a 1X.

3 years might have been early enough before real standardization of hardware.

I wonder if a weak burn by the CDRW might have contributed?

Steve


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Subject: RE: TECH: How long do CDRs last?
From: JohnInKansas
Date: 11 Aug 02 - 11:14 PM

Don't know if anyone is still interested, but John C. Dvorak's Inside Track column in the September 3, 2002 PC Magazine comments:


"What's with 48X CD-R Burners? Dept.:

"It's been interesting to watch the evolution of the CD-R recorder. Everything began when someone came up with the idea that you didn't need to burn a pit into a CD to make a writable CD. All you needed to do was make something that looked like a pit. A gob of goo or a change of color would do.

"This led to the development of three separate CD-R worlds. The inventor of the technology was Taito Yuden, with the cyanine-disk strategy The medium was the original write-once disks—emerald green or cobalt blue—and the early ones still provide the most compatibility, in my experience, with older CD audio players. The early versions of this technology are believed to have a short life of 20 years or so. With later implementations, this has been improved to 70 years.

"Taito Yuden licenses the technology to just about everyone. I have seen it produce disks with 32x write speeds, and there may be faster formulations. Most of the TDK disks found at Costco are cyanine.

"Then came Mitsui Toatsu with its phthalocyanine disks. These are the popular disks with a light-greenish-yellow hue. This technology has also been licensed to just about everyone. Most of the ultra-cheap disks you fmd at Best Buy are of this type. They are supposed to last 100 years.

"The newest technology is the secretive Azo formulation developed by Mitsubishi. This disk has a pretty sky-blue appearance. Azo is pushing the high-speed envelope, with Verbatim licensing the technology and promoting 40X and 48X write speeds. I expect even higher speeds as companies such as Plextor and TEAC make high-speed writers. Azo disks are also supposed to last 100 years, and they are currently considered the premium disks.

"CD-R drives have to account for all the variations, and that's where compatibility problems occur. If you have an old CD-R disk that doesn't load fast, I'd consider making a new copy. Mucking up the scene are some Asian dye makers that have created variations of the licensed technologies. Their disks may not work well in all writers.

"From my perspective, the writable-technology wars have begun in earnest."


I'd divide all the "life" figures by at least 5 for any disks not stored in the dark, with temperature/humidity control, and a good insect control program, but at least Mr. Dvorak outlined what competing kinds of media are available.

John


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Subject: RE: TECH: How long do CDRs last?
From: NicoleC
Date: 11 Aug 02 - 11:56 PM

Interesting quote, John. My experience has been that I get great results with Maxell and Verbatim, and everything else I've tried is complete trash. Maybe that's why.

DAT tape is magnetic, so it has a shelf life of about 20 years, max.

L.G., for archiving photos, the best method is still processing on high quality paper, storing in a dry, dark place when not viewing, and never, never covering them with plastic or leaving them next to paper with acid in them. Photo albums with "magnetic" pages are just about the worst thing you can do for photos.

The paper & processing matters a lot. Older b&w/sephia photos have a lifespan of 200+ years, and genuine b&w processing is still the longest life. Color processing is getting better, but early color photos are already severely degraded.

Our family has some very old photos, going back to the Civil War era. A few years ago I did an archival-quality album AND scanned everything, burned them on CDs, and distributed them to lots of family members. The album cost a small fortune to make, but it was worth it. It seemed the safest way to preserve them for another 4 or 5 generations.

Color laser prints also have a very long lifespan. No one knows for sure, but the estimate is 100+ years.


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Subject: RE: TECH: How long do CDRs last?
From: GUEST,misophist
Date: 12 Aug 02 - 10:14 AM

Don't be so unsure of tape storage. Remember the bad old days when all commercial music storage was on reel to reel tape? If you use a professional tape transport and store the tape properly, it will last for decades. The enemies are light, heat, and chemical degradation; and tape stretch with the resulting wow and loss of coating.


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Subject: RE: TECH: How long do CDRs last?
From: treewind
Date: 12 Aug 02 - 10:37 AM

Tape has been used for storage because that's virtually all there was, but tapes have to be kept in cool dry conditions and also have to be taken out and exercised (run from one spool to the other and back) periodically to prevent print-through from becoming permanent.

Years ago the BBC didn't trust tape and kept all their sound archives on vinyl, which if you don't play it too much is pretty safe. I don't know what they use now.

Nobody's mentioned Magneto-optical disks yet. That is a very robust and stable storage medium. I have 230Mb and 650Mb M-O drives and like them a lot. Also more recently a DVD-RAM which is M-O technology storage in CD sized format, and 4.7GB per disk, or twice that if you use double sided. Minidisc also uses M-O recording and is thus a good option for long term storage.

By the way, I use a Plextor CD burner and once I sorted out a HD performance problem that was causing buffer underruns, I have been able to burn cheap disks at x24 routinely with no failures. I don't know what Plextor do that other manufacturers don't, but they have a good reputation and I have no regrets about paying a little more for a burner that I can really trust.

Anahata


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Subject: RE: TECH: How long do CDRs last?
From: Mr Red
Date: 12 Aug 02 - 11:02 AM

IN the early days of CD'r there was a lot of talk of the Gold coloured disks being a better bet. It was found that the varnish on silver ones was liable to etch the aluminium (aluminum for the US catters) whereas gold was was virtually impervious. THEN it was revealed that commercial CD's also suffered - particulalry early ones and cheap ones. They have sorted it but on which brands of CDR is not going to be clear - buy brand names is my advice. I intended archiving all the Pagemaker, Graphics and PDF I am creating - 30 Meg of PDF - 420 pages - and most of the text has survived 10 years on floppy in PM4 guise and was copied from 360K floppies in CPM format then


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Subject: RE: TECH: How long do CDRs last?
From: NicoleC
Date: 12 Aug 02 - 12:42 PM

Hey misophist,

Magnetic tapes are notoriously unreliable, in a large part because or the numerous types of materials used. (Backing material, type of metallic particles, binder, lubricant.) A cheap home cassette is toast in under 10 years; the very finest professional tapes under perfect storage conditions have an theoretical expectancy of about 50 years if the tape itself has absolutely no physical flaws.

But does it really matter if CD's last 100 years? We won't be be able to play them on existing equipment 100 years from now. The only solution is to do what archivists do, and refresh the media periodically with new copies; retaining the old ones if possible. With digital media, at least the loss of quality when copying is extremely low.


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Subject: RE: TECH: How long do CDRs last?
From: Mr Red
Date: 12 Aug 02 - 06:10 PM

Got more time now
In my exerience I have lost less than 5% of my floppies and there were plenty of duplications - a policy designed to protect against magnetic failures. The worst losses were in the days of using cassettes tapes - micro cassettes.
so my policy for achival will have to be a selection of brands and duplications. It is pretty important and is going to be a few Gigs of graphics. The only alternative to CDR is leaving it on the hard disk and the failure rate there is running at worse than 5%!


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Subject: RE: TECH: How long do CDRs last?
From: GUEST,JTT
Date: 12 Aug 02 - 06:35 PM

There was a story about a year ago about libraries panicking and backing up all the material they had stored on CDR, putting it on to something else - hard drives? - as well.

The reason was a fungus that attacks the surface of CDs, making them unreadable.

Not sure where the story was, maybe the Guardian or the BBC.


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Subject: RE: TECH: How long do CDRs last?
From: johnross
Date: 12 Aug 02 - 11:23 PM

We're facing the question of long-term survuval in the NW Folklife audio archive project. The archival community has not accepted any single standard for audio archives, so various archives are using different apporaches.

Our plan is to make the master digital copies on two sets of hard drives, with a third set of CD-R copies. The hard drives will be twice the definition (in bits per second) of audio CDs. I'm reasonably confident that this will give us at least one set that somebody can use 50 years from now.

Other archives are using quarter-inch analog audio tape, or DLT format digital tapes. Nobody seems to like DAT, because it has dropouts.

It's my understanding that archival-quality CD-Rs (Mitsui, Kodak, maybe T-Y) can be expected to last at least 50 years. All bets are off with cheap consumer CD-Rs.


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Subject: RE: TECH: How long do CDRs last?
From: delphinium
Date: 13 Aug 02 - 01:00 AM

There is much discussion of these issues by archivists (surprise), and lots of relevant but not definitive info on archives and library web sites. I'm not a techie but here's my 2 cents worth re the "non-technical" basics, as learned from an electronic records archivist colleague:

The 3 "enemies" of preservation of electronic records are, in this order:
  1. Obsolescence of the software to read the files.
  2. Obsolescence of the hardware.
  3. Degradation of the medium that holds the digital information.
For this reason the preferred place to preserve electronic records is on your hard drive. Better to buy more memory and keep your files where you have a better chance of knowing what's happening with them and where they will be migrated forward through any upgrades. If you use CD-Rs to "archive" your files, use good CDs, good procedures (including quality control checks), keep them compatible with your software and hardware, and be prepared to burn new ones about every 3 or 5 or 10 years. Guess it depends on how important they are to you (a risk analysis thing).

The preservation issue is one side of it, but there's also the disaster recovery issue – hard drives crash, get viruses, etc., so you need back-ups. This is where CD-Rs and other off-line media are really valuable.

For back-ups my colleague recommends using either a good quality CD-R (gold, with phthalocyanine organic dye, they look light green) or DLT (digital linear tape). There are ANSI (and possibly ISO?) standards for CDs now, and probably for the processes of writing them too, and better quality makes a difference.

Magnetic media of today can be as good as or some say better than optical media like CD-Rs, if properly made and stored. Manufacturers of both claim that they will last 50 or more years, but the archivists I know don't trust them more than 3-7 years. (As stated by others, commercially pressed non-writable CDs may last longer than CD-Rs.) Treewind, I don't know much about magneto-optical disks but they seem to be widely used. The general advice for long-term storage is stick to something that is widely available and well supported, it's more likely to work in the future.

If you REALLY don't want to lose your digital information, keep it on more than one medium. We have loads of digital photos and music as well as the home business records and other stuff, and we just added a new pair of twinned hard drives. We mirror the hard drive, and we also back up the important files to CD-Rs (Maxwell) regularly and keep them in a different place. Something like John Ross's archives.

And of course, whatever media you use should be stored properly. Some basics for CDs and tape cassettes: relatively constant temperature and humidity (the ideal is about 18-22C and 35-45%RH), handle by edges, with clean hands (cotton gloves if you're an archivist), store CDs in polypropylene or polycarbonate cases (I think they're the sort of frosted but slippery feeling ones - don't use paper), store vertically, keep them in the dark, label CDs with special markers (not adhesive labels), etc. And you probably know, if you need to clean a CD, move from the centre to the outside across the tracks, not in a circular around-the-tracks motion.
Oh yes, the mould story. I'm told it can happen to CDs but not a real problem unless you leave bits of food on them…


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Subject: RE: TECH: How long do CDRs last?
From: GUEST,Mr Red at library
Date: 14 Aug 02 - 08:38 AM

I had a pre-emtive strike at archiving on CDR last night and bugger me if a TDK blank refused. My cheapo 80 min ones (for the price of a pack of mints) saled through without a hiccup. More scratches & without even a top/bottom identifier and not much to distinguish even that. BUT at least I got to first base.
The TDK refuser has no physical clue to its failure.
I think the Gold disks at ten times the price are going to be the best gamle.
The music industry had this as well. They recorded on VHS tapes with an industry standard digital archiving process, except Decca who invented their own. Ten years later and they find that not only are they getting print through (literally the magnetic domains from the spiral layer above changing the bits) BUT the tape was sticking together and ripping-of the magnetic particals. The solution was to bake the tapes and that mostly worked. Music has been lost in that archive format forever.
Decca did not have that problem because they used reel to reel and the tape used different binders for the magnetic particles.
The moral is - Duplication & Using different media spreads the risk.
No how reliable is the Aural / Oral tradition?


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Subject: RE: TECH: How long do CDRs last?
From: John J
Date: 15 Aug 02 - 08:59 AM

Refresh...this is a most interesting thread.

John


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Subject: RE: TECH: How long do CDRs last?
From: Mr Red
Date: 15 Aug 02 - 10:27 AM

Just a thought but I have had several opinions that archiving on the net is probably the most reliable. Well run ISP's will have back-ups of back-ups and re-instate if there is a problem. But longevity and the net are not proven bedfellows and maybe the clues are negative. Still it is a thought.
With the inexorable slide in the price of silicon we might expect Flash (etc) to be cost effective soon, how important are the data?


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Subject: RE: TECH: How long do CDRs last?
From: GUEST,JTT
Date: 15 Aug 02 - 10:29 AM

So what would archivists use to save their own most precious files? Hard drives?


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Subject: RE: TECH: How long do CDRs last?
From: Bill D
Date: 15 Aug 02 - 10:34 AM

I dunno..but this thread is a scary revelation...I have burned 10-15 reasonably important (to me) CDs in the last year....now I have to consider re-doing them?? *sigh*

Where are the label warnings..."Notice...this medium is not intended for lon-term archival use"


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Subject: RE: TECH: How long do CDRs last?
From: treewind
Date: 15 Aug 02 - 10:46 AM

Golden rule of data preservation: always have at least two copies of everything.
An interesting truth has emerged form this discussion: data archival is not a static thing. The way to keep your data is to keep copying it: that way you are not dependent on the long life of any particular media, and you can upgrade to newer technology when it becomes available.

Digital storage enables this process to be continued indefinitely, whereas analogue audio recordings will eventually deteriorate, whether by media failure or copying.

Anahata
(in philosophical mood)


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Subject: RE: TECH: How long do CDRs last?
From: robomatic
Date: 15 Aug 02 - 12:58 PM

Very good topic. My personal experience:

Cassette tapes. I have about 200 of 'em half that have personal meaning to me, some as old as 30 years. No more than 5% are giving me problems, and several of them are because TDK made a C-180 that was so thin you could see through it! Try splicing that mama!

I'm playing the cassettes into my computer doing a 16 bit Analog to Digital and recording to my hard drive via Cool Edit. Mostly happy with the results. I've been able to do this with LPs and take out skips, which is fun.

Some CDR's are obviously cheap. CompUSA store brands have the reflective layer on the outside of the top of the CD. They are worse than worthless. If you write on the CD or scratch that surface you can lose the playability of the entire CD.

I recently tried out a Philips audio CD recorder. Reason was it purported to be a time saver, allowing you to play an LP into the machine which would immediately burn to CD and interpret the record bands as unique CD tracks. This saves a ton of time over playing the LP into a computer, then utilizing an editing program to locate, separate, and name all the tracks.

Unfortunately the Philips FW-R33 doesn't correctly identify the LP tracks. It also only uses 'audio CDRs' which are more expensive than basic data CDRs which computers can use. When I called the Philips help line, they blamed the brand of CDR media I was using, and told me not to use certain other brands. This would have been helpful if they had printed it in big letters on the box, because they are the most available and least expensive brands in my area.

My solution is to go back to data CDs and the more laborious computer treatment. And to leave much of my archived music on a large hard drive, duplicated on another large hard drive, and to have one of those drives on a computer which never goes online (to avoid viruses, worms, and bacteria).


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Subject: RE: TECH: How long do CDRs last?
From: GUEST,steve.peach@ntlworld.com
Date: 15 Aug 02 - 04:47 PM

Regarding longevity of audio 'home-brewed' CD-Rs: I've found that one of mine, in WAV format, must have been played 20 or 30 times. (sad, or what ?) This is still going strong; so I think that careful storage of discs and use of a reliable burner are paramount.


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Subject: RE: TECH: How long do CDRs last?
From: Mr Red
Date: 15 Aug 02 - 07:38 PM

If all you want to archive is text you might try printing it out. There are papers they reckon will survive 400 years (who validates the guarantee and is the receipt on the same paper?).
The problem with paper archive is twofold. The quality of OCR and the longevity of the ink -
xerographic processes should be OK but inkjet I wouldn't put any money on even if kept in the dark. Still my Cannon prints have survived 10 years with no appreciable dimming.
Flash memory makers claim sort of 100 years or a million reads levels.


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Subject: RE: TECH: How long do CDRs last?
From: GUEST,Mark Ross on the road
Date: 16 Aug 02 - 01:42 AM

The older the technology the longer it lasts. Consider, for instance, Carved in Stone!

Mark Ross


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Subject: RE: TECH: How long do CDRs last?
From: JohnInKansas
Date: 16 Aug 02 - 04:41 AM

W.e.l.l..G.u.e.s.t..M.a.r.k. -

At the cemetary down the road from me, most of the stones that are approaching 70 or 80 years old are mostly illegible. 'Bout the same life the makers are quoting for their photoplastic CDs...

We'll need a discussion now on what's the best kind of stone - and how deep you need to carve it(?).

John


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Subject: RE: TECH: How long do CDRs last?
From: GUEST,Gurney
Date: 16 Aug 02 - 06:50 AM

The same question came up in 'Ask Cecil' this week, and the answers from his research are all in these posts. It depends on: Quality of media. Conditions of storage. Loss of play technology. My own thought was, is the laser lower-power in playback than in recording? Will the laser cause erosion? Should we only play back on a CD reader? Gurney.


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Subject: RE: TECH: How long do CDRs last?
From: mack/misophist
Date: 02 Sep 03 - 09:50 AM

The manufacturer's claims for cd-r's have always seemed like so much hot air to me. Now some of the bad news is starting to surface. This came up this morning.Click Here


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Subject: RE: TECH: How long do CDRs last?
From: WFDU - Ron Olesko
Date: 02 Sep 03 - 10:09 AM

I think the moral of the story is you get what you pay for. This report seems to focus on cheap discs.

CD's and DVD's are not the format for long term storage, but they are also much better than this misleading report. There are no ideal formats - tape will lose oxide, discs and records will scratch. If you have something that you value dearly, you should make multiple copies and replace copies after a few years.


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Subject: RE: TECH: How long do CDRs last?
From: mack/misophist
Date: 02 Sep 03 - 01:59 PM

The report does focus on cheap disks. The point is, if one technology has been hyped well past acceptable limits, what does that say about a very similar technology. After all, it's very unlikely that anyone has tested to the limits of their claims.


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Subject: RE: TECH: How long do CDRs last?
From: WFDU - Ron Olesko
Date: 02 Sep 03 - 02:09 PM

I don't think that is a very fair statement concerning testing to the limits ... after all, if I tell you that I get 30 miles to the gallon in my Saturn but then do a test on a Hummer and find out it is getting 10, is it fair to say that all car mileage claims are wrong?

As you point out, the report is focusing on cheap discs. I'm not sure what two technologies you are comparing, I may be missing the point you are trying to make.


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Subject: RE: TECH: How long do CDRs last?
From: mack/misophist
Date: 02 Sep 03 - 05:42 PM

The biggest difference between cheap and expensive disks, other than quality control, etc, is the dye used in making them. That and something involving multiple layers that I don't really understand. The good ones advertise hundreds of re-writes and a decade or more of stability. I wonder how they know.

A brilliant engineer might be able to compare the specs of a Saturn and a Hummer and decide which was more efficient, I don't know. Take half a ton off the Hummer and they may be the same.


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Subject: RE: TECH: How long do CDRs last?
From: GUEST,WarDog
Date: 27 Oct 03 - 02:38 PM

From what i have found TAPE backup last the longest, i have a old 1gb tape backup that i've had since around 96' and it still reads fine with no errors, although i goto the trouble of storing my media the right way, in a static free sealed cabnet....hell when i think about it i still have a C64 and with the old 5.25 and regular tape drives and all the software i have for it still works fine, and i must have got that in about 1987 or 1988...


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Subject: RE: TECH: How long do CDRs last?
From: Burke
Date: 28 Oct 03 - 12:26 PM

I haven't read it yet, but NIST Special Publication 500-252, Care and Handling for the Preservation of CDs and DVDs - A Guide for Librarians and Archivists, probably covers most questions.


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