Hello all,
We finaly found a solution!
The problem was with the RAID controller. Intel RSTe seems not to be supported by the installer. Curious thing here is that by shell you can mount and write on the disks that installer cannot see.
By reading some docs of the server, we found a BIOS upgrade that changes the Intel RSTe to "VROC PreOS" as described on the next link. https://www.supermicro.com/Bios/softfiles/9992/P-X10DRT-P-PT-PIBF-PIBQ_BIOS_...
After performing the update, Qlustar can now see the disks. It still cannot se the RAID volumes of the controller, but from now we can install the SO.
Thank you Roland and Goswing for your help and support.