How to test my WD myBook Duo on Mac?

I have a MyBook Duo connected to my Mac for about 3 years now - working smooth for the last years.
Today now I heard the fan is very loud running so I wanted to do a check.

I started the WD Drive Diagnostic and was prompted to update - did this - the ran the Quick Drive Test - result was “no errors” - the ran the “long drive test” - but that “crashed” and stopped at about 20%.
I tried again but the test only works up to 20-30% and then gives an error “test failed”.
After that also the Quicktest only goes until 30-40% and then fails.

My fans are still running loud - but I experience no problems with the drive running my data and backup.

I now just wonder if there’s ANY other software that can run a drive test - Apples internal test only fails too.

And with the WD tool also just "fail"ing and not giving ANY information back I have no idea what may be wrong.

My drives are in RAID (2x4TB mirrored) so I cant just connect and test them on another machine (that I also dont have).

Found this website but it’s a windows application I believe