What happened was that I have a mirror RAID (RAID-1) and one of the drives died.
As far as I know, one should always use identical drives for mirror RAID (don't mix iszes, don't mix manufacturers, right?), but I can't afford 2 right now, so I bought a new Hitachi 2tB to match my old Hitachi 2tB - the difference being that the old one is SATA 2 and the new one is SATA 3.
The J-micron RAID controller does not see the new drive ... can it be that the MSI P35 Neo3 motherboard does not support SATA 3?
Or is it something else?