Digital media is a double-edged sword. Digital data itself can be duplicated an unlimited number of times without any generational loss – meaning it can theoretically last forever. But digital storage on physical media is subject to failure – and that failure can render the data inaccessible. In other words, archivists (including you) have to transfer data before the media fails.

And we’re already entering an age when one of the most popular formats is reaching the start point for common failures.

A report by Tedium (republished by Motherboard) demonstrates one of the most alarming failures. Some media, evidently using faulty dyes, can fail in under ten years, via something unpleasantly dubbed “disc rot.”

The Hidden Phenomenon That Could Ruin Your Old Discs

At issue is the fact that optical media uses a combination of different chemicals and manufacturing processes. That means that while the data storage and basic manufacturing of a disc are standardized, the particulars of how it was fabricated aren’t. Particular makes and particular batches are subject to different aging characteristics. And with some of these failures occurring in less than ten years, we’re finding out just how susceptible discs are outside of lab test conditions.

In short, these flaws appear to be fairly widespread.

That just deals with a particular early failure, however. In general, CD formats start to fail in significant numbers inside 20 years – on average, not just including these rot-prone flawed media.

What’s tough about this is that the lifespan can be really unpredictable. Before you dismiss the CD as a flawed storage format, many discs do reach a ridiculously long lifespan. The problem is really the variability.

To get an accurate picture, you need to study a big collection of different discs from a lot of different sources. Enter the United States of America’s Library of Congress, who have just that. In 2009, they did an exhaustive study of disc life in their collection – and found at least some discs will be usable in the 28th Century (seriously). The research is pretty scientific, but here’s an important conclusion:

The mean lifetime for the disc population as a whole was calculated to be 776 years for the discs used in this study. As demonstrated in the histograms in Figures 18 and 19, that lifetime could be less than 25 years for some discs, up to 500 years for others, and even longer.

COMPACT DISC SERVICE LIFE: AN INVESTIGATION OF THE ESTIMATED SERVICE LIFE OF PRERECORDED COMPACT DISCS (CD-ROM) [PDF, Preservation Directorate, Library of Congress]

Other research found failures around 20-25 years. That explains why we’re hearing about this problem round about now – the CD format was unveiled in 1982, and by the 90s we all had a variety of optical disc storage to deal with.

There are two takeaways – one is obviously duplicating vital information on a regular basis. The other, perhaps more important solution, is better storage. The Library of Congress found that even CDs at the low end of life expectancy (like 25 years) could improve that lifespan by twenty five times if stored at 5 degrees C (41 degrees F) and 30% relative humidity. So, better put that vital collectors’ DVD in the fridge, it seems. That means instead of your year-2000 disc failing in 2025, it fails in the 27th Century. (I hear we have warp-capable starships long before then.)

But anyone using discs for backup and storage on their own should take this even more seriously, because numerous studies find that writeable CD media – as we purchased with optical drives in the 90s – are even more susceptible to failure.

There are many other issues around CDs, including scratch and wear. See this nice overview, with some do’s and don’ts:

CD and DVD Lifetime and Maintenance [wow, 2007 Blogger!]

Or more:
CDs Are Not Forever: The Truth About CD/DVD Longevity, β€œMold” & β€œRot” [makeuseof]

I’ve seen some people comment that this is a reason to use vinyl. But that misses the point. For music, analog storage media still are at a disadvantage. They still suffer from physical degradation, and reasonably quickly. For digital media, hard disc failures are even more frequent than CDs (think under three years in many cases), and network-based storage with backups more or less eliminates the problems of aging generally, in that data is always kept in at least two places.

The failure of CDs seems to be more of a case of marketing getting divorced from science. We’re never free of the constraints of the physical world. As an archivist will tell you, we have to simple adapt – from duplication to climate control.

But I’d say generally, with network-connected storage and automation, digital preservation is now better than ever. The failure point is humans; if you think about this stuff, you can solve it.

But ideally digital preservation should not use optical discs because of how unpredictable they are, and because these failures can prevent data access entirely. In particular, writeable discs are very much prone to failure, and if you have data on them, you probably want to consider retrieving that data and putting it on another medium sooner rather than later.

And it’s about time to start heeding these calls, given that they’ve been widespread since the turn of this century. For instance:
IBM expert warns of short life span for burned CDs [PC World, 2006]

The solution then? Tape.

  • TeamOth

    Well my dubnobasswithmyheadman CD rotted (first from the inside out and then the outside in) in less than 2 years. One day I’ll get round to replacing it.

    • How about MP3 files? πŸ˜‰

      • Tom

        Those begin rotting as soon as they are made.

        • synapticflow

          Oh. har har! lol.

        • commodore256

          What’s wrong with MP3 that isn’t wrong with DVD Video?

          Lossy Audio is no more bad than Lossy Video is bad and where’s your lossless video?

          • Dan Martinez

            Because lossless audio is small compared to lossless video .. Because lossless audio can be played from any speaker .. unlike losslessvideo

  • patrick h. lauke

    Possibly a more insidious problem waiting to happen with harddrive/solid state drive based backups is that these can “silently” get corrupted. If backup systems then simply copy what’s there without checking timestamps (e.g. just copy “anything that’s different” rather than “anything that’s newer than the backup), the corrupted/broken files may end up overwriting the good/non-corrupted version that’s already on the backup…

    • That is indeed also an issue, but I am sure this is well known by anyone who uses (classic) hard disks or even solid state disks for backup? The only way to be safe is by introducing redundancy. I’ve got my entire Mac backed up on an external hard drive, plus everything valuable in the cloud. There’s no other way, IMHO.

      • patrick h. lauke

        my point is that those backups (be it on external drives, or the cloud) need to stay in sync, and that because of this it’s possible that a subtly corrupted file is perceived by some backup software as a “change” which then gets sync’d to all other locations…meaning your silently corrupted file overwrites the backed up good versions. and you wouldn’t realise the file was silently corrupted until you then opened it in the relevant application…

        • Dan Martinez

          Yeah that happened to a few of my songs ;0;

  • Rex Wesley Reyes

    Damn…not exactly what we were promised back in the 80’s. Oh well, i’ve started buying records again anyway.

  • Robin Parmar

    This is old news as some disks were unplayable a decade ago already. No medium is forever. Did anyone actually believe the marketing hype?

    • There was a recent report at the top … another look at disc rot. I think the further out we go, the more data points we’ll get. That 2009 Library of Congress report is probably the most interesting just in terms of volume of data.

  • Valued Customer

    Moral: Periodically verify and migrate your data, people. Assume nothing – this problem is real. Interestingly, I saw this happen way more frequently with laserdiscs than any other format. Nevertheless, I long ago started keeping multiple, verified computer copies of my entire audio and data CD collection, because of how ephemeral digital media formats, whether they be optical or magnetic. So if you care about it, verify it periodically and make enough copies (including offsite ones) that you’re as covered as can reasonably be expected.

  • Ooops, where did this discussion come from, suddenly? I thought, we had left CDs and DVDs behind already years ago? I haven’t used CDs or DVDs for data backup since I don’t know how long. But I definitely remember having had many disks that turned bad in very short time, even though I stored them in a normal dry place, not exposed to sunlight and at normal room temperature. It certainly sucks, when you take out a CD or DVD and find the silver surface being separated from the clear plastic disc… But is anybody still using these disks, really?

    • Actively, probably not. But have they necessarily removed all archives off of this media? I think it will continue to resurface so long as there are waves of failure.

      • SevenEyeballs

        For data backup, sadly no.

        Even though I have dozens of DVD-Rs just lying there in a spindle.

        However I just bought a used copy of Sasha & Digweed’s 2000 mix ‘Communicate’ on two glorious CDs via my local record store.

        It is such a joy to turn my car on and immediately have a high fidelity disc in rotation for only $2.99.

    • William

      The quality of music on a CD is superior to download music via iTunes though most people aren’t acoustically aware to be able to discern the difference.

      • True, but that was not my point. I referred to CDs or DVDs as data backup media.

    • Robert Wheeler

      Hey, I know this is an old thread but trust me, I still use CDs, and DVDs. Not because it’s some great medium or I don’t know how to use USB drives. But not everyone has converted their stuff yet. Not everyone has USB access in their autos, ect. It’s still a highly relevant medium. That’s why Walmart still sells them. If there wasn’t a market, nobody would buy it. But some still do. Heck I got people who still buy VHS tapes!

  • heinrichz

    How about DAT tapes?

  • LeBlanc

    Well you can just download flac files of your corrupted CD’s from a torrent website. I know downloading is illegal but in this case you already paid for that music. The record company sold you the music on an inferior medium so that’s why I don’t see a problem with downloading…

    • synapticflow

      Yeah, but no site has everything. Well they are some that claim to, but they’re like some exclusive club reserved only for Morpheus, Neo and Trinity.

  • Alexander E. Wahl

    Too bad! I always hoped future generations would discover my hard-disks and cd-r’s full of unfinished tracks and celebrate me as an ancient, misunderstood artist.

    • Doug Gough

      Glad to hear I’m not the only one entertaining this fantasy πŸ˜€

    • Brad Hall

      Pretty sure they won’t be able to read them as they don’t have a laser 7 output πŸ˜‰

  • Ekadasi Newton

    Ever heard of the M-Disc? M-Disc DVD or BD that uses a stone like alloy said to last one thousand years… That alone changed my view on optical media. All forms of magnetic storage are sensitive to magnetics or all kinds… A RE magnet, an electrical spike or magnetic storm or an EMP would affect tape while Optical media will remain unaffected.

  • synapticflow

    I’ve had CDs rotting long before they should have. It seems to only happen to the ones that have no colored decorative coating on the top side.

  • commodore256

    A lot of Console fanboys think just because they have a disc, their games will last forever and digital downloads don’t. At least you can backup digital files, gog has no DRM. Consoles on the other hand have had DRM since the NES.

    • Dan Martinez

      The NES doesn’t have DRM .

      • commodore256

        The NES had a lockout chip, it was a form of DRM to try to prevent backups and homebrew. (though it was circumvented years ago)

  • (shudder) I have two sets of portable hard drives that are just for back up exclusively. The only time they see any activity is like once a week or month. Didn’t know HD had a higher rate of failure than CDs. That kinda sucks.

  • The

    Society has this weird fascination of archiving every bit of history ever recorded. But some things are meant to die out. Things like star wars will always be around. But the 1932 recording of twinkle twinkle little star from a then 8 year old from Alabama doesn’t need to be kept forever.

  • Pete Farrow

    The person who wrote this article is completely ignorant of averages (i.e. stupid). If you think an analogue tape is going to last 776 years then you are even dumber. So here it is for those of you (the author included) who does not under stand averages. Mathematics
    : Averages : Lesson one. The average lifespan is 776 years,
    this means on average discs will last this long, some may last a lot
    longer some may last a lot less. So its just meddling with the numbers
    to say “some may last over 500 years” when in fact probably 70% will
    last over 500 years because half will last over 776 years – that is what the mean is. My entire CD collection which I started in 1983 with an Aretha Franklin CD is absolutely fine. This is just click-bait shit talking article.

  • Pete Farrow

    oh, and they obviously never heard of M-Disc. I guess that’s why they
    are journalists, they don’t actually know anything and are constantly
    uttering nothing technical, as those in the know say,

  • Pete Farrow
  • CDMan

    Badly written, misleading article. The article makes it sound like your CD collection is rotting away and will be rendered useless in 25 years. Yet the study says that on average CD’s have been calculated to reach a lifetime of 500 to 700 years, but that “SOME” CD’s fail within 25. Well obviously not all CD’s are of the same quality. If your CD doesn’t last longer than 25 years, then it’s probably due to it’s cheap shoddy production, not the format itself.

    Some iPhones explode, some colostomy bags leak, some Uber drivers are drunk, some people on craigslist are serial killers, some Taco Bell employees spit in the food and some farts are wet.
    It’s the exception that proves the rule, it doesn’t mean we should expect those things

    Fact is that CD’s are the most stable and best way of storing your music (as all the idiots who store their music on hard-drives are about to find out). Oh, and if you’re one of those people who rips lossless audio CD’s to compressed mp3 files and then throws away the CD to save space, then you shouldn’t worry about losing your collection at all…..you already have (Go ahead, tell me that audiophiles are just talking out of their ass and that there’s no difference between mp3 and flac. Which you’ve assessed after comparing the two with your 3 dollar earbuds which you got from a box of cereal).

    So go ahead hipster millennials, Call me a dinosaur and laugh at me all you want. I’ll listen to my CD’s whilst you keep throwing money at Apple every year for their new iScam which is going to be old and unsupported the following year. Let’s see which format lasts the longest.

    Oh and btw. for all you vinyl supremacists claiming vinyl is the master race. If you actually played them instead of bragging about them to your hipster friends, you’ll notice that they’re far from ideal.

  • Lance Smith

    “Disc rot” was a manufacturing defect on PDO pressed discs prior to 1998. The discs I own which have experienced playback issues and discoloration are all PDO pressings from the Blackburn pressing plant which was shut down after a major problem was discovered during the mid-1990s. The flaw was apparently caused when the plant used hard water during the disc wash, which was followed by application of the lacquer coating. The water supply in the ara of the Blackburn plant apparently neglected to flush all of the pre-lacquer process contaminants away and in an ideal world, the product probably should’ve been recalled. However, an estimated 5 million CDs were affected during this window of time.