I have a 2x 4TB My Book Duo which is 2 years old. In that time I have experienced 3 RAID failures, which could only be resolved through a complete RAID rebuild, with the consequent nuisance of having to backup nearly 4TB of data and then copy it back to the My Book Duo once it has been restored. I use Mac OS 13.6.
On all three failures I got a warning that there was a RAID problem, and could see the tell-tale red light flashing slowly on the front of the unit. I was advised to run WD Drive Utilities. This informed that one of my drives had failed. The data was accessible on the other drive.
This happened within a few months of buying the unit, so I doubted WD Red drives would have failed so soon. By removing each of the drives, and booting them individually in the My Book enclosure, I found I could access the date on both drives, so clearly I was being misinformed by WD Utilities that one drive had failed. However the only way to restore the RAID 1 format I had been using was to reset RAID configuration, which erases all the data.
This has happened 3 times in 2 years and has eroded my faith in the My Book Duo as a reliable archive. I imagine the actual problem is some kind of fault or corruption of the raid management firmware, but it is hard to be sure. Has anyone else experienced this? After resetting the RAID configuration my unit is once again registering as ‘healthy’, but I am having to recopy all my data from an alternative back-up onto the My Book Duo. If I have to keep yet another backup because of repeated failures of the RAID system, it defeats the purpose of having it.