2x2TB is not believed be possible. It is said tivoapp cannot handle more than 2TiB of mfs address space, or something like that. I believe it is the tivoHD that was the first to use a 64 bit mfs, and even it cannot get past 2 TiB. That was the point I was working at when I commented about dual drive setups. It is now possible to get a tivo to the maximum capacity it can handle with a single disk.