Even archive quality CDRs stored optimally (in cool and dark place) can fail in under 10 years. I had some recorded in 1999 that started having errors this year (checked once a year for viability). And these were special CDR media (Verbatim super dye) that costs 20x the normal CDR price, so really best case. I seriously doubt that any CDRs will survive 30 years, and most fail before 5 years. DVD+R lasts much longer than CD-R (estimated 100 year life) due to a different recording technique and better error correction (not true of DVD-R). Moral of the story: copy any CDRs that you want to keep onto fresh CD-R media every 3 years, or copy to DVD+R.