SegaXtreme

I don't want to be banned or anything, but I've had this question on my mind for a few days. how is it even possible to copy GD-ROM games? I mean, they use about 1 gig of data (well, probably only the launch titles could be copied), and the largest CD-R is 700 mb at the moment. Plus don't they use some kinda multi-code thing for the data like PSX games? And no I don't even have a DC.