Hardware Failure? Or File System Failure?

I have a 2nd gen Drobo that’s been running well for several years. I had computer problems with my Mac last week resulting in a lot of hard-disconnects for the Drobo, but it seemed to be working fine. Got my desktop repaired yesterday, rebuilt, and reconnected to the Drobo last night and was getting files on and off of it with no issue.

This morning, my Mac had a notice on it that the Drobo disk had been removed without ejecting. I thought that was odd, but the drobo was still turned on, just not seen by the system any longer (including disk utility and Drobo Dashboard). I power cycled the Drobo, and it then showed up in Disk Utility, but not mounted. An attempt to mount it returned a message that the volume could not be mounted and that I should attempt a repair. The repair ran and returned a message that the disk could not be repaired, and it suggested a format and restore from backup. My Drobo is using over 4TB of space, so I don’t have a full backup.

Drobo references elsewhere using the program DiskWarrior to help in this situation with a Mac, so I purchased a license of the software for $100 and ran it. DiskWarrior initially reported that a recovery was not possible on the drive due to hardware failure but after a few minutes switched to recovery available. I ran recovery and DiskWarrior reported hardware issues through the recovery several times, and ultimately after several minutes said it could not recover the volume. “Directory cannot be rebuilt due to disk hardware failure (-36, 2747)”.

What’s odd is through all of this, Drobo Dashboard continues to show the Drobo unit as healthy and all disks show green.

I pulled the power from the Drobo and let it sit a while and then powered it back on. DiskWarrior again indicated it couldn’t start a recovery due to hardware failure, but again after several minutes DiskWarrior switched to recovery available. Instead of using Disk Warrior I switched back to Disk Utility and attempted repair again. This time it came back clean, ran through a repair, and mounted the Drobo volume.

The Drobo has continued to run all day. I’m just confused as to whether it’s a problem with my file system or with the Drobo itself. I’m open to getting a new Drobo to migrate to, but Drobo support has indicated that if it’s a file system error that I would be migrating the problem.


Its quite hard to discern the cause of the fault. It might had been the unit, the drives or a file system issue.

In any case, I think it is best to backup your data if you had not done so. If you have the latest firmware installed (1.4.2) you could look into migrating your disk pack to either the Drobo Gen 3 or the Drobo 5D.


hi, id also suggest backing up your data, eg do it now while you can access it
(dont forget to try and verify the copy of the data too, as best you can)