Welcome to Tom's Hardware, halu42!
This seems very unfortunate!
I hope you have a backup of the data stored on the RAID 1 because, unfortunately, it's not a good backup solution.
Since those two WD HDDs were your system drives as well, your option to troubleshoot their health and check up on their SMART data is through DOS.
You should run
WD's Data LifeGuard Diagnostics for DOS (once you select your WD HDD product, you should be able to see the software file), but first, you'd need to create a bootable flash drive with the utility. I'd recommend you to follow
the instructions here.
Hope it helps you. Keep me posted with the results.
SuperSoph_WD