Any way to get it back to system as the "old drive".
With the Toshiba hard disk and if it is not defective and disk 1 would be recognized again, the parity would be valid and I only have to rebuild the second parity instead of rebuilding one parity and one data disk which is actually the same as before.
I powered of the system, changed power cord and unplugged and replugged the sata data cable and now the HDD is back again.
Looking forward if some errors appear again.
At the moment I use 3 power cords from one PSU to the HDDs, some of them with splitter, some without.
backup-diagnostics-20240220-1918.zip