It is a well known fact that the CD-R’s and DVD-R’s that you burn at home won’t last forever (neither does factory made media, for that matter, but that’s another story). Exactly how long is impossible to answer. It depends on the quality of the disc and how it has been stored. But the CD-burner and (as we shall see) the CD-reader matters as well. The tricky part is that you can never really tell the condition of a disc until you try to read it. And by then, it might be too late.
This article details my experience of copying more than 400 discs, ages varying from 3 up to 14 years old. First a bit of background. Over the years I’ve managed to collect a rather large amount of music, video clips, pictures, games and other “fun stuff” that I’ve come across. Back in the days, hard drive storage was expensive and online services such as Spotify and YouTube did not yet exists. Burning CDs was the only reasonable way to have a large media library. It was always my dream to one day be able to “return” these files to my computer. The developments in storage technology have been incredible, and today optical discs are no longer viable as archive media (in fact, they are more expensive than hard drives per megabyte!). So a while ago I decided it was time to do it. This meant that I had to copy more than 350 CD’s and about 70 DVD’s. The oldest CD’s in my collection were from 1997, and the oldest DVD’s from 2005. In total there were roughly 375,000 files weighing in at over 550 gigabytes!
I’ve always been aware of the inherent problems with degrading optical media. To be safe I mainly used brand name CD-R’s, preferably the “blue” ones as they were rumored to be of higher quality. Of the various brands I used, Verbatim stands out as my favorite brand, but I also used discs from TDK, Kodak, Sony, Samsung and BASF. In addition to these I also had a few odd brands and some “no-name” disks. For a long time I kept the discs stapled at my desk in their jewel cases, but 6 years ago I consolidated them all into CD-spindles, which I then kept in a dark locker.
I always kind of dreaded this moment, because I knew that many of the discs might turn out to be unreadable. In retrospect, I can only conclude that everything went better than expected. Here are my results:
- Of the 420 discs, a total of about 20 discs had read errors or other major problems that stopped me from copying them. Many other discs were difficult to read, but made it through in the end.
- Many (not all though) of the unreadable discs were no-name discs (i.e. cheap discs without labels, usually with a more or less unprotected “mirror” surface on top). I’ve always been suspicious of them, none the least since the data layer is so thin that you can often see through it if you hold the disc in front of a light! In other words, it’s no surprise these would be among the problematic discs.
- More surprisingly though, four of the BASF discs had read errors. Given that I only had 10 of these in total, it’s not a good result.
- An entire “batch” of discs from Verbatim had such severe problems I had to abort reading them since I feared the drive would break or overheat. Additionally 2 Verbatim discs from other packages failed on a few individual files.
- Now, all optical drives have built-in firmware that determine how it operates. This leads to differences in between readers depending on the manufacturer and firmware used, especially in more extreme situations such as when the error correction must kick in. Thus, having attempted to copy all disks using my ordinary drive as outlined above, I took the erroneous discs and tried to copy them on another computer (with a different CD-rom drive). This reader worked much better and actually managed to retrieve most of the problematic data! A few faulty discs remained though. I decided to give it a try on yet another computer, with additional success!
- In the end, less than 10 discs, all of them no-name brands, were unreadable to some extent. Most of them did not contain any important data, so I did not bother to test them in yet more computers. Thus it is fully possible that some of them were actually readable given the right circumstances.
In summary, everything went better than expected. The number of problems were quite small given the amount of data. I was able to retrieve almost all the data, although I had to try three different CD-readers before success with all discs. Brand names and quality discs do matter, but is not a guarantee for error free operation. About 2% of the discs were unreadable in the end. This may or may not be acceptable, depending on the purpose. I am certainly impressed though, that the very first CD-rom I burned could still be read without problems after 14 years!