There is a problem with Drobo Devices connected via Thunderbolt and Mac OS Big Sur RC2 (and probably Big Sur Release). Their Customer Support page says: "NOTE:

There is a problem with Drobo Devices connected via Thunderbolt and Mac OS Big Sur RC2 (and probably Big Sur Release). Their Customer Support page says: "NOTE: Drobo Thunderbolt had been working properly up to RC2 posted on Nov. 11. If your Drobo has a USB port, use this. In the interim we are looking into the issue. " My experience is a combination of kernel panics on startup, volumes not mounted, and not showing a filesystem in the Disk Utility. I was worried I'd lost all my data until I ran across this and was able to plug one device in via USB. Unfortunately, my Drobo 8D doesn't have a USB port, so I'll have to wait for a software solution.