I have two G-RAID 2x6TB Thunderbolt 2 drives, one for each of two older Mac Book Pro’s running Mac OS Sierra. When first purchased (less than a year ago) I used the Configurator to set both of them for RAID 1. These drives are used for both Apple Time Machine system backups and for large photo repositories - different directories, same partitions. Both drives worked fine - until I upgraded both Macs to the latest Mac Book Pro’s running Mac OS Mojave. Both drives are connected to the new Macs via Apple branded Thunderbolt 2 to Thunderbolt 3 (aka USB C) adapters and both drives appear on their respective desktops and can be read and written to without apparent error.
However, one of the drives is now displaying a constant red LED indicating (I assume) a failed drive. The Configurator for this drive reports “No device found”. In troubleshooting, I find the Configurator on the other Mac with the “good” drive (white LED) also yields the same “No device found”. I haven’t yet tried accessing the drives via USB (which will obviously also require an adapter).
How do I access these drives to determine whether they are mirrored and how do I fix the “red” drive?