hello i've been using D5 DVD (4.7GB) solely for many years and i've never used any other DVDs, now for some business purposes I have to use D9 DVD because D5 DVD is not enough. I'd like to know if majority of DVD drives nowadays can also support D9 DVD if it supports D5. I know it might be a silly question but I want to make sure that. Thank you.

DVD-5 holds 4.7GB and is supported by the DVD+R/RW and DVD-R/RW formats. It is also known as Single-Sided Single Layer.

DVD-9 holds 8.5GB and is supported by the DVD+R and DVD-R formats. It is also known as Single-Sided Double Layer (sometimes called Dual Layer). The official names are DVD-R DL and DVD+R DL

Kenny in short.. a DVD-9 is basically two pressed plastic DVD-5s pressed together, which are not burned

oh people say actual usable size of a D9 disc is only 7.8-7.9GB, while a DVD-5 is 4.3GB, but the average price of a D9 disc is usually double to that of a D5 disc, why people still use D9? By the way, how about Double layer DVD?? Can I use them to store data? OR should I upgrade to blue-ray? I don't watch HD video but I need a lot of space to save mpg/avi/asf video etc.

Those can be used to record but not write.. and as for blue-ray *Shrugs* that's over my head, I only know the basics no more since I don't use them..

if a DVD player can read the data from a DVD-5 disc, does it imply that it can also read from a DVD-9 data disc?