two discs was not enough and didn’t work very well, as id Software’s Tim Willits is confirming that the upcoming release of Rage for the Xbox 360 will come on 3 discs, not two discs as some had reported. The total installation on your Xbox 360 hard drive will be about 22GB, and installing it on the hard drive will be the way to go.
Apparently, id has come up with a method that will allow each disc to be individually installed one at a time as the player progresses though the game. If you don’t have the disc space you can install the first disc and then once Chapter 1 is completed; you can install disc 1 and install disc 2, which of course has Chapter 2 on it. Once you are done with the previous disc, there is no need for you to go back.
The PlayStation 3 version, which comes on a single Blu-ray disc, will only require an 8GB install on the hard drive for the game. This will be a one-off 8GB install on the hard drive and the game reads any other data it needs from the disc. The massive storage of the Blu-ray disc is clearly an advantage here.
While unconfirmed by Willits, it is widely now believed that the PC version of Rage will also come on 3 DVDs and require a 25GB installation to the hard drive.
Read more in Willits’s interview here