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Up To 10% of CD-Rs Fail Within a Few Years
Whatever you think about the likelihood that a new kind of DVDs could last for 1,000 years, this note from reader crazyeyes should give you pause about expecting current CD-Rs to be reliably readable for decades. TechARP found a failure rate near 10% for CD-Rs recorded 7 to 9 years ago, after storage in ideal conditions. On some, one or more individual files could not be recovered; others were not reliably readable on two separate drives. "In the past, hard disk drives were small (in capacity) and costly. To make up for the lack of affordable storage, many turned to CD-Rs. As it became common to store backups and personal pictures, videos, etc. on CD-Rs, the lifespan of these discs became a concern. According to manufacturers, CD-Rs should last for decades. Some even quoted an upper limit of 120 years based on accelerated aging tests! That sure is a long time, isn't it? But will CD-Rs really last that long?"
I've experienced this myself lately with a bunch of disks that were now useless. It was cheaper off brand disks that failed. The irony is at the time I got them, they were the ONLY disks I could get to work on my CD player.
So far I've had no failure with CD-R's from Sony, TDK etc... Which were the disks my CD player simply would NOT play.
i have entire 1995 to 1998 CD-R spindle's and all 400 of them still function just fine. i recently had to run trough all 400 of them, and had zero read errors. i guess my discs are possessed by some magical force, or this is just bogus.
I've had CD-Rs and DVD-Rs that I burned over a decade ago still read fine. However, those disks were verified burns where I immmediately read back the data with Nero to make sure they were ok.
There was a time when I didn't do verified burns. Those disks have a ridiculously high failure rate, but I'm betting they were bad burns in the first place. With most media I get close to a 10% failure rate on verifying the burns.
I do not fail; I succeed at finding out what does not work.
I recently tried reading a bunch of audio CD-Rs burned between 2003 to 2007. I used Exact Audio Copy on a Toshiba drive. I was able to get error-free reads from about half the disks recorded in 2003; about 3/4 of the ones from 2004, and from all the ones recorded after that. On the early ones that worked, sometimes EAC took a couple of hours to do the reads, which means it was doing a lot of retries. On the later ones, the transfers were mostly just a few minutes. On the ones that reported less than 100%, sometimes EAC spent 50-60 hours trying.
For the disks that I could not get 100% reads on from the Toshiba drive, I tried them in several other computers using a variety of programs. Mostly I was not able to get results as good as EAC on the Toshiba drive. I tried two Mac Mini's using Max and an old Mac G3 using cdparanoia from the command line, and got lots of failures. Then I tried Max on my MacBook and they all read perfectly. Go figure.
I theorize that one reason the disks had errors was that they were labeled using a Sharpie. According to the NIST report on CD-R failures (nvl.nist.gov/pub/nistpubs/jres/109/5/j95sla.pdf), this is a really, really bad idea. Since I read that report, I've been adamant about using only water-based markers on CDs and DVDs.
I used to work for a company that burned about 100 CDs a day. Half were kept as "backups" on site. The other half were shipped off to clients that were only going to use them once to transfer the days data to their server.
About 4 years later we lost a drive array and wanted to restore from the CD backup. I set one of my people to offloading the CDs to a new set of drives. Meanwhile I went to our offsite backup and copied the relevant data back to the server in a few hours. Days later my employee comes back to me and says that "most" of the CDs are coasters and the data is gone. It turns out that about 1/3rd of the CDrs either didn't burn properly in the first place, or had failed in the 2-6 years they were on a shelf.
The lesson was a simple one. The offsite backup server was faster, easier and more reliable than the CDRs. Of course, management blamed the (long since) fired employee that burned most of them. They also paid 5k$ for a brand new Mass burner / labeler, and used up nearly a week of production time getting it working and tested.
A year later the clients all moved to USB thumb drives and or FTP transfer for the data, making the fancy mass burner obsolete.
Back in the earlier days of CDR, a "high speed recorder" was recording at a whopping 4x or so. As drive recording speeds increased, the CDRs rated for those higher speeds had to become more responsive to the laser hitting it for a shorter period of time. How do you accomplish that? One big way was spreading the dye out in a thinner layer. That's likely to have a negative effect on longevity.