360 DVD data limit is 6.8 GB

[MikeB]

A summary from my perspective based on discussions.

Early XBox 360 drives were slower 12x drives, later 360 drives are faster and 16x drives are in use on the 360 today.

The inner most part of a 360 disc needs to be dual layer, is read first and includes video files and other stuff. The drive rotation speed remains constant across reading discs, thus data at the outer part of the disc is read faster than the inner parts. 360 games are thus optimised to place read speed critical data at the outer part of the disc (but thus involves higher seektimes, as normally a disc is read from the inner parts towards more outer parts of the disc).

There are many early XBox 360 games which only use a single layer (~3.4 GB), when creating an image file for storage onto the harddrive most likely this just involves one layer switch (faster like creating an image file of a 3.5 inch Amiga disc is much faster than normally copying a 3.5 inch disc scrammed with many files), layer 1 is read and copied then layer 2 for DL data (~6.8 GB, like Microsoft said). This is different from game data reading which involves lots of layer switching.