Hi,
alec:
I've never had a CD or DVD fail unless the burn didnt work, but i have had rewritable CD's and rewritable DVD's fail after only one or two writes! That was nasty as those were more expensive. I dont buy that junk any more now.
It could have something to do with the drive too. Is the laser diode old perhaps, does it burn right in the first place. I say this because there have been extensive studies done on CD's that show that they have very long life when stored properly. Oh yeah, they have to be stored properly too, up on edge i think not flat like old LP records.
Timescope:
Built a small mini CNC station, where you use an aluminum disk as the platter. Have the CNC station (just an automatic drill press) bore tiny holes in the surface of the aluminum disk. Bore a deep hole where there is a 'zero', and a shallow hole where there is a 'one'. Store the disk in oil.
Should last for a while
Regardless of the media type the only sure way seems to be to make many copies of the original data. Two copies isnt too bad, three copies better, four copies better yet, etc., etc.
Another technique is to 'layer' the backups. Make one backup then next backup goes to a different media. That way if one media fails you have the other backup which is slightly out of date but not as bad as nothing at all.
But unless you have tons and tons of data to store you should be able to find a way to do it with today's available media.