The new FAI release 4.2.5 fixes the problem that setup-storage does not work with empty disks when using a Jessie nfsroot. This was because parted >=3.X changes some output. Thanks to Mika for the patch.
You can get the new packages from the FAI project package repository by adding deb http://fai-project.org/download jessie koeln to your sources.list files. -- regards Thomas