It seems this problem has come up a few times (mine is a Drobo 5D DRDR5A), but all links suggesting solutions seem to no longer exist.
I had a 4tb drive fail (the rest are 3tb), i swapped it out for a new one. About 15 hours into the data rebuild (of expected 24) the drobo had unmounted, but i left it for 12 hours or so as i was concerned that it was still rebuilding.
The following day, and after it still hadn’t mounted i turned it off on the switch on the unit, turned it back on and it mounted, yet it then started to reboot itself during data rebuild, sometimes after a few minutes, sometimes after a few hours. I was concerned this was going to corrupt the other drives so when it had switched itself off for a reboot i removed the new 4tb drive.
The unit mounted in data protection mode and seemed stable, so i took the opportunity to start to back-up important data. After 12 hours or so, the drobo continued to reboot itself, usually after only 2 minutes of mounting. Since all of this, 2 of the 4 remaining ‘good’ drives now say ‘healed’.
The only thing I’ve tried so far is removing all of the remaining 4 drives with the unit off, running the unit empty to mount, powering down, and then reinserting the drives again when the unit is off.
I’ve read online of people putting the unit into read-only mode but can’t find instructions on how to do this; I’ve also read that a user had to clone a drive to get the disk pack working happily again, but didn’t suggest how to distinguish which drives need cloning.
Massive thanks in advance for your help,