You can extend the lives of writable and rewritable optical media by proper storage. The key is to avoid light and heat as much as possible, to keep the dyes stable. I'm not sure about 30 years, but you can probably get 10 out of properly stored optical media. See the following advice:

>A disc should always be handled by grasping its outer edges, center hole or center hub clamping area. Avoid flexing the disc, exposing it to direct sunlight, excessive heat and/or humidity, handle it only when being used and do not eat, drink and smoke near it. Discs should be stored in jewel cases rather than sleeves as cases do not contact the discs’ surfaces and generally provide better protection again scratches, dust, light and rapid humidity changes. Once placed in their cases discs can be further protected by keeping them in a closed box, drawer or cabinet. For long-term storage and archival situations it is advisable to follow manufacturer instructions. For further information consult the international standards for preserving optical media (ISO 18925:2002, Imaging materials — optical disc media — storage practices). [0]

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[0] : http://www.osta.org/technology/cdqa12.htm

> You can extend the lives of writable and rewritable optical media by proper storage. The key is to avoid light and heat as much as possible, to keep the dyes stable. I'm not sure about 30 years, but you can probably get 10 out of properly stored optical media.

Though, if you care about longevity, it might be better to use a technology like M-DISC. It uses a different recording technology to "[burn or etch] a permanent hole in the material, rather than changing the color of a dye."

https://en.wikipedia.org/wiki/M-DISC#Materials_technology

Yep...not to mention all discs are ultimately made of plastic which is subject to environmental degradation - primarily oxidation from atmosphere and UV damage, both which can lead to yellowing/clouding of the transparent medium, and eventually brittleness and fracture.