DVD and CD rot

[cathodraytube]

one agen its another thing thats been floating around in my head and bothering me for a while ......how long will dvds and cds REALY last?? .iv been reading about this alot i want to know if any one els has ever had a case of disc rot and what everybody elses idias are on the subject. i personaly dont own any dvds but i do have some cds that are starting to show signs of rot (brownish rings/stains and some little pinnholes in the aluminum). as far as i know about disc rot is that its caused by air getting to the aluminum/gold/silver or whatever els ther using as the reflective layer and oxidizing it ...that and inpurities in the metal eating it away . also? how long will tapes last?? ...some of my tapes (video and music) are 30+ years old and work fine ...and why dont they make cds/dvds in some kind of cassette to keep them from getting dirty/scratched ...like floppies and zip disks have???