I tried to build a Mirror "Raid". The devices are shown in physical disks (sdh and sdi), there I wiped them. When I now try to build the RAID, only one (sdi) of the 2 disks are shown in the list. They are both connected with USB on the system.
The same is when I just try to make a new filesystem... in the drop down list is only sdi ... sdh is missing there, too.
Where can be the problem? What can I do?