How long will CD-R's & DVD-R's last?

FWIW, I've heard that the Library of Congress still archives recorded material on good old analog vinyl!

I have read in one report that claims DVD+/-R will only last as short as 2~3 years. when I told my friends and we are all engineers and one of them used to work for a lazer diode company that read/write DVD, no one believed me. but it got me worried and I did archive more often now since media is so cheap.

I have many CD-R audio disc that were burned in 2000 and still sound the same as the day I made the copy. These are the Disc made in Japan. Maxell and Sony made by Taiyo Yuden.

quote from wikipedia:

Main article: CD-R
A typical 700-megabyte CD-RRecordable compact discs, CD-Rs, are injection molded with a "blank" data spiral. A photosensitive dye is then applied, and then the discs are metalized and lacquer coated. The write laser of the CD recorder changes the color of the dye to allow the read laser of a standard CD player to see the data as it would an injection molded compact disc. CD-R recordings are permanent. The resulting discs can be read by most CD-ROM drives and played in most audio CD players. Over time however the dye will fade causing read errors and data loss until the reading device cannot recover with error correction methods. [citation needed] This time can be anything from a few months to a projected life of over 100 years, depending on the quality of the discs used, the quality of the writing drive, and storage conditions.

http://en.wikipedia.org/wiki/Compact_disc

It would appear from the article the burn side is light sensitive to ultraviolet light. When not in use I keep the disc in a CD jewel case with the label side up.

Just an added note, what I have found is never demagnetize a CD-R Audio disc after it has been burned. It will sound dead..... Why? I have no idea, but it does.

Nobody knows.

I just hold in my hands HP 650MB CD-R that I burned in early 1998. It is almost 9 years old and sounds fabulous. I also have many DVD+R disks burned more than 3-4 years back. Every disk is like new.
Greetings
Plutos