I have replaced both 2T drives for 6T drives in my My Cloud Mirror configured as a RAID1. It went well, the size available remained at 2T as expected. I then tried to Expand the capacity to take advantage of the extra space using the menus Storage/RAID/Change RAID mode/Expand Drive. Nothing seems to be happening and I have the message below that says “Remove Drive One”.
For more than 24 hours the RAID Profile displays:
Expanding, Volume_1 is expanding. And RAID
Expanding. Remove Drive1.