A longstanding installation of TimeMachine was working with Big Sur 11.2.1 on my Drobo 5C except I could no longer delete files from within TimeMachine (the Delete option is no longer visible). Is this expected behavior, please?
So, I deleted and reinstalled Time Machine, unfortunately, Big Sur/TimeMachine formatted my 5C drives as APFS and two of the four WD Red disks gave a “failed” message in the dashboard. The dashboard version is 3.5.2 .
So, I reset my 5C and reformatted the four WD disks, including the two “failed” ones and so far everything seems OK.
I have had to stop using TimeMachine for the present and am using Carbon Copy Cloner instead. I do understand that Drobo has said that APFS is not currently supported by Drobo but feel that they also should have included the statement that new installations of TimeMachine are not imported.