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Actually, discs do have a life span, and it is very short compared to flash memory. According to the official BluRay website, BluRay discs have a 10-15 year life span.
http://www.blu-raydisc.com/en/aboutblu-ray/whatisblu-raydisc/bdkeycharacteristics.aspx
Compare this to flash memory, which is only getting longer and longer.
In 2009, a record was achieved with 1 million write cycles. (
link)
Only 3 years later, in 2012, 100 million write cycles was achieved. This is 100 times the life span in only 3 years. (
link)
For reference, 1 million cycles, on the low end, will last approximately 27 years according to
this article. For moderate use, that could multiple by as much as 10 times or more. Assume moderate use at 10 times 27 years, 1 million write cycles will last 270 years, whereas 100 million will last 27,000 years. For high use, current technology puts it at 2,700 years. (27 years was only for 1 million which was years ago, because it's now more than 100 million write cycles). Also keep in mind that 100 million cycles was a couple years ago. We might be at 10 billion cycles by next year, which for moderate use will be 2,700,000 (2.7 MILLION) years.
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