Longevity of DVD-R and CD-R (Was MagTapes)

[Eric F.]

Richard Bristol wrote:

 > (5) I don't burn more than 85% of the capacity
 > of a DVD. DVDs are a sandwich, lexan (polycarbonate)
 > on both sides, data layer chemistry in the middle.
 > The spiral starts on the inside (opposite LP records).
 > If you leave 3/4" unused at the outside edge, it will
 > take longer before the Ozone and 02 and other environmental
 > exposures that attack the data chemistry at the edges
 > of the lexan sandwitch actually reach your data. So on
 > a "4.7GB" disk which in real life could hold 4.3GB, I
 > burn 3.8GB.


Interesting approach.

Curious though ... why do the edges get attacked first?  Are the disks 
slapped together in some sort of fashion such that there exists a potential 
breach at the edges?