As long as a CD/DVD is not used to support external weights, it hardly matters whether they are stored Horizontally or Vertically. Theoretically, a CD/DVD kept horizontal supported only at the ends can deform due to creep - over a period. The point is, this period is long enough to make the contents obsolete even for the archives.
Keeping them cool and in dark enclosure is the best way to preserve for a reasonably long time - say 6 to 8 years. I don't think any other means can guarantee infinite life.
Ramesh
[quote]Discs last longest when stored in plastic cases in a cool, dark, dry environment. Because gravity can gradually bend the disc, storing it upright like a book is best for long-term storage. [/quote]
http://webcache.googleusercontent.com/search?q=cache:Z8ck53_oPNIJ:askville.amazon.com/store-CD-DVDs-long-term-storage-plastic-jewel-cases-vertically-flat-albums/AnswerViewer.do%3FrequestId%3D2975556+jewel+case+upright&cd=9&hl=en&ct=clnk&gl=ca&source=www.google.ca
so does this mean that pressed disc, inside a cd jewel case or a dvd case, must to be stored in vertical position to ensure that it doesn't get bent by gravity?
thanks for letting me know!

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