Are these SMR drives? I know WD failed to disclose the downgrade until people called out the BS but I believe it should be labeled now. Either way, my understanding is that SMR doesn't start to kill performance until there is a heavier transactional load. A straight write to empty disks shouldn't be impacted. I don't know if I'll ever trust WD again after all that but I don't think it has anything to do with sververda's concerns.
The WD drives are actually CMR, so not SMR. It's hard to say what i expect from these drives as there are no real tests that i can compare to with the motherboard raid from the Z690 chipset. So my expectations are very loosely coupled to what i saw from the synology tests with the same drives (they actually tested both the CMR and the SMR versions) minus the (as from what i have read so far) a slight performance drop because of the sofware raid. But to be honest i already would be really happy if i only am able to achieve half the writing speeds that i saw on that synology.
Tnx so far for the answers, i do know ofc that other raid options like going for raid 10 will give better performance... and hey who knows in the end i will make it a different setup but right now i prefer the capacity over the write speed. Read speeds from this setup while copying files back to the NVME are satisfactory for me and overall i will do much more reads then writes to the raid 5 (it was just very annoying while moving all my data from the older disks to the raid).
I will certainly do some more tests on the raid setup with the various caching options disable and will let you know the results.