Hello, Im using 5D3 for 2years, I use Toshiba 10tb x5 , Im using Macbook 2019 , update to Big Sur, I had update my Drobo to latest firmware. The Bay1 always show red light and sometimes show Hard Disk Failed. I had replace the bay1 hard disk with new one with Toshiba 12tb, and it is working for couple minutes, It disconnect after 5minutes and start showing bay 1 is empty.
It’s possible the backplane (the part the drive connects to) has failed for that bay. You may be able to verify this by shutting down the Drobo, rearrange the drives then power it back up. If the failure stays with bay 1 then that is where the problem lies.
Yes, you can rearrange the drives within Drobo, just make sure it is OFF before beginning and they are all firmly seated before turning it back ON. As long as the drives remain together, their order does not matter.