Thunderbolt Duo RAID Rebuilding Itself in MacOS Sierra


I have a 6 TB WD Thunderbolt Duo, which is set to a RAID 1 mirror configuration.

Every time I reboot my Mac, the RAID becomes degraded and the auto-rebuild process starts. Needless to say, I feel this is putting a lot of unnecessary strain on the drives apart from being a general annoyance.

I found what appears to be an excellent WD support article on this exact issue here:

Unfortunately, when I try to execute the last command to change the RAID timeout from 30 to 60, I get the error message “Error updating RAID: Couldn’t modify RAID (-69848).”

Does anyone know how to fix this error so that the command is executed?

Thank you in advance.

What happens if you try to run the command from another Mac that is not using Sierra?

Thanks for the response.

I tried on both an El Capitan and MacOS Sierra machine, but the result is the same. Do you think it’s related to the SIP that Apple introduced with El Capitan? Perhaps the WD Support article hasn’t been updated to account for SIP.

Hi Eusebius,

I have a similar setup as you (6TB, Raid1, Sierra) as you. and also the same problem.
With “diskutil ar list” you can see a more detailed status about the rebuild. When I found this, I waited till the rebuild was finished, it took about 15 hours! So don’t shutdown your Mac before. At the moment it’s running fine.
Like you I wanted to set the timeout as described in the article you linked, I also got this error message, even when I turned off SIP. Hafe you found a solution for that?