How Long Do CDs Last?

Vitaliy_Kiselev

Back in the 1990s, historical societies, museums and symphonies across the country began transferring all kinds of information onto what was thought to be a very durable medium: the compact disc.

Now, preservationists are worried that a lot of key information stored on CDs — from sound recordings to public records — is going to disappear. Some of those little silver discs are degrading, and researchers at the Library of Congress are trying to figure out why.

Testing found that not all CDs are the same. The outer coating of some CDs erodes, leaving a silver layer exposed. And when you leave silver exposed, it tarnishes.

"By increasing the relative humidity and temperature, you're increasing the rate of chemical reaction occurring,"

Researcher France says many of them can actually last for centuries if they're taken care of. "The fastest way to destroy those collections is to leave them in their car over summer," she says — "which a lot of people do."

http://www.npr.org/blogs/alltechconsidered/2014/08/18/340716269/how-long-do-cds-last-it-depends-but-definitely-not-forever

brianl

What's your opinion for archive? LTO? This subject has been driving me crazy for ten years.

Vitaliy_Kiselev

@brianl

Just use mirrored HDDs and remote backup for anything most important.

neokoo

For those interested, here's an article about basic problems involved in data preservation ("Avoiding a Digital Dark Age" by Kurt D. Bollacker): http://www.americanscientist.org/libraries/documents/2010241629167775-2010-03CompSci-Bollacker.pdf

As I currently understand, for music and general audio storage, vinyl or comparable material that can be read with multiple devices (laser, stylus, optical) is one of the best backup options available. It'll degrade, but if something were to happen to digital archive copy (EMP, deprecation of codecs, whatever..) the analog one can at least be read, and the knowledge to build a vinyl player can be easily preserved in a book.

Black and white film (three strips for full color) is probably still the most robust analog archival option for video data. Haven't seen any small scale filmout companies offering such services though. It's both sad and funny, everyone is using hard drives and solid state devices for their data storage, but hardly anyone could retrieve the data themselves, without knowledge and resources of huge technology company.

4CardsMan

Back in the 90's, I warned my IT clients about this. One insisted on archiving Autocad drawings to CD anyway. My strategy is two fold: (1) Keep the original clips intact on their memory cards and buy new memory cards as needed for new projects and hope the data survives, and (2) archive everything to a hard drive, replacing the drive and turning over the data every few years. (2) mimic's nature's strategy of DNA replication, which will work as long as someone keeps it up after I am gone. Transfer to separation negatives would be ideal, but as neokoo says, this service is not generally available.

DrDave

In answer to the question, I have a large enough statistical sample to draw some conclusions. I first started recording CDs around 1996; Yamaha made a 4x recorder, the CDR100 (please do not ask how much this cost). A 1gb drive was the max I believe.

http://books.google.com/books?id=K8IS2A_xDLUC&lpg=RA1-PA146&ots=Pej8qNTVC5&dq=yamaha%20cdr100&pg=RA1-PA146#v=onepage&q=yamaha%20cdr100&f=false

In the worst case scenario, I had CDs made by CMC Magnetics (sp?) that degraded within a year. In the best case scenario, some of these are still fine.

So we can derive from this the following: there's no way to know in advance, and it can be a short time. Bad media is more likely to degrade rapidly.

OTOH, the media I have purchased that is special archival grade, so far no worries. I burn two masters, store them in a dark, cool drawer. I also use special burners that produce larger pits on the CD (Yamaha burner).

After burning the master, a digital image is made. Using Plextools, the image is checked bit for bit against the master copy. is uploaded to the cloud and also saved on old, smaller hard drives that have been replaced by larger ones. As long as the cloud exists, you can make a bit for bit master from this digital file.

Lastly, I have a drawer full of two types of burners that are super readers. Plextor and TDK. There are several of these that have extra error checking hardware that will read a so-called unreadable disk

Ausboy

For what it's worth I pulled out some project on 11 year old CDs and couldn't read em on my blu ray drive at all. Thought they had gone to data heaven. Caused my computer to freeze a number if times. Pulled out my ancient laptop from 2006 and voila. Read right off the bat with no issues at all. Perhaps that is another complication to add. Newer tech that is supposed to be backwards compatible but isn't quite.

brianl

How come LTO never gets any love? What's the downside to it?

DrDave

@brianl LTO in the form of magnetic tape has a shelf life of 15 to 30 years according to Imation. You can assume that the "chance of fail" is more like 7 years. Compare that with the 100 to 200 year shelf life of the top archival disc media.

There are also M-Discs, no one knows how long they will last. The dye is inorganic. http://en.wikipedia.org/wiki/M-DISC

hini

Try DVD-RAM http://en.wikipedia.org/wiki/Dvd_ram Much more reliable.

goanna

We just have to accept it: long term archiving is not yet with us. So every few years we have to copy our data to new media.

Individuals show little preparedness to go to this effort, so there's a good market still out there for professional archiving services.

brianl

goanna, the strange thing is it seems there is no demand for great archival formats. I don't get that. This is an ephemeral time I guess.

Vitaliy_Kiselev

the strange thing is it seems there is no demand for great archival formats. I don't get that. This is an ephemeral time I guess.

Something tells me that it is not strange. Corporations are not interested in cheap easy way for preserving information.

soundgh2

Warner Bros here in the UK who are one of the clients we provide audio for use LTO as do most post houses in London that I know of - everyone's about (again) to go tapeless - SR tapes are still being used to originate the master audio and video and performing archive duties. Audio stems and the various video output takes an age to do and changes, again take an age to remake, so financially more money drained from the ever dwindling resources. But hey the BBC et al get to sack 20 QC people so result for the man.

A lot of productions also don't budget for long term storage of the projects (especially multi cam gigs etc) as they really "don't" have the cash due to the influx of younger first time prod managers trying to come in UNDER budget to impress, rather than the usual 20% over to preserve the emergency margin and next years buffer.

It's all a squeeze!

DrDave

I have tapes from the 60s. They are a mess.

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