Memories of a great vacation may last a long time, but do the photos you've taken on that African safari and copied onto a recordable disk hold up over the long haul? That's what reader Allen Shattuck wants to know. He writes: I recently read an article that said CD-R and CD-RW disks used to store photos only last two to five years. The article stated that heat can degrade the recording surface of burned CDs, making the stored data unreadable by laser beams. I was under the impression (perhaps mistakenly) that digital images stored on CDs would last indefinitely.
Since they are relatively new, the exact longevity of recordable CDs isn't really known. The Optical Storage Technology Association (OSTA) gives a "conservative" longevity estimate of 5 to 10 years. I suspect that OSTA is being overly cautious, and you can expect a good bit more life than that. Their optical disks should be far more durable than magnetic media, which deteriorate relatively rapidly unless re-recorded from time to time. Magnetic films -- tape and floppy -- are the first to go. Optical media -- CDs and DVDs -- do better.
FADE TO BLANK.Commercially produced disks use tiny pits stamped into polycarbonate plastic. The main risks to the integrity of the data are scratches and corrosion of the reflective metallic layer. However, the data on the sort of recordable disks you are asking about are burned into a dye layer and could become unreadable if the dye fades.
The main risk would be exposure to direct sunlight, but I have never experienced such problems. Keeping any sort of media away from extreme heat is a good idea. Digital media won't warp like vinyl records when left in your car on a sunny day, but high temperatures will definitely shorten the life of any media.
In general, the biggest risk to data is not deterioration of the media but technological obsolescence. I still have some 5 1/4-inch and even some ancient 8-inch floppies around, but I have no idea if they are readable because I have nothing to read them with. I keep a USB floppy drive on hand, but I can't remember when I last used it.
PAPER TRAIL. These days I use USB memory keys for the jobs once assigned to floppies, but these aren't permanent either -- unless powered up occasionally, the flash memory will eventually fade too.
If you really want to save data for the long haul, libraries and conservators say your best bet is black laser printing on acid-free paper. Stored in a dry dark place, the pages should last for well over a century. And unless the art of reading dies entirely, there's no risk of technological obsolescence.