The organic entity known as Sparky communicated the following:

Tom Scales wrote:
Two layers.

Which means twice as much data per DVD. The single layer DVDs hold 4.7
GB, the dual layer ones 9.something

I think the correct number is something like 8.5 GB.

I haven't gotten deeper into the technology, so I am unsure if that is a
technology maximum or just the maximum of the currently available drives.

--
Hans