@pocopicoExcellent Job. Thanks a lot!
After a litte while and understanding SataPortMap and DiskIdxMap my Dell T20 appears to run nicely on DSM 7 (previously 6.something)
The output of the rploader script was providing
64 for SataPortMap and
0004 for DiskIdxMap -
if I remember correctly.
First controller 6, second controller 4 ports. So far, so correct but not all ports are in use.
So I figured out for the first controller 4 drivers were in use and for the second 2 drivers plus 1 USB Key.
I changed
SataPortMap to 421 (4 drives on controller 1, 2 drives on controller 2 and 1 usb key)
DiskIdxMap to 000406 (00 for drive 0-3, continuing 04 for the following 2 drives and 06 for the USB key)
I hope I correctly remember the values (System is currently busy) and the values might help others.
Thanks again!