The disk handling code in anaconda has been entirely rewritten for F11, so we're expecting issues in this area and we really need people to file reports when they come across them. However, we do need a lot more details
As the others asked, please explain exactly what you've tried to do and what happens when you do it, and some information on your hardware: ideally, what disks do you have, and what disk controllers. A Smolt profile would be great if you have it. Thanks!