How long an ordinary DVD can keep data in the ideal conditions?

Answer 1

Unknown. The technology is too new. Engineers have ideas, but only time will tell. They used to say that Beta and VHS would last 100 years. That has yet to be proven. I have old tapes that are as good as new. I have newer tapes that were trash when I bought them. I have better success with audio tapes. If you don't use them, vinyl records never lose data. Too bad you have to use them and wear them out. Good question.

Answer 2

So far : proved to keep data for over 40 years with neglectible loss.

Answer 3

I thought its lifetime if kept safely