Fixing Drobo 5D not appearing in Finder

22 November, 2016

My father's Drobo (a Drobo 5D with 18 TB of space) was malfunctioning ever since he updated to SierraOS without first disconnecting the Drobo. At least from what we can tell, that was the catalyzing event.


  1. Can see the Drobo in Disk Utility, but 'First Aid' fails
  2. Using terminal, $ diskutil list shows the three partitions (EFI, GUID, Data) but trying to either mount or unmount using $ diskutil mount or $ diskutil mountDisk fails
  3. Cannot see the Drobo in Finder or access the data in any obvious way
  4. Same or very similar symptoms in Windows (I didn't check linux)


  1. DiskWarrior

I fiddled for days trying to force mount the device, but DiskWarrior fixed it instantly. It's pricey, but for a first try fix I figured it was worth it!