I have a Drobo with 4x2GB disks installed to hold all my stuff. ALL my stuff.
The other day, I connected to Drobo in order to execute a TimeMachine backup. Drobo came up green yet Finder did not mount it. I heard rumbling noises and knew that something was messing with it. I just was not sure whether it was Finder or the Drobo's firmware itself.
DiskUtils could not access the disk. Big panic. Called Drobo support and was surprised by their shallow "do a repair" reply.
I stumbled upon the following procedure by poking around and taking chances. I was "this far" from writing off 3TB of photos and projects, so I felt I had nothing to lose. Please note that in no way can I guarantee that this will help you, but it worked for me:
1. The rumbling noises that I heard when I connected the Drobo to the Mac were due to Finder trying to mount the disk but with running FSCK prior to doing so. The rumbling was probably due to a screwed up MBS.
Disk Utils was hampered as long as Finder was messing with Drobo, so I killed it:
2. Looked for any disk-related tasks by 'ps ax' in terminal.
3. Killed those tasks using 'sudo kill -9'
4. That left the Drobo in the exact state I wanted it: Unmounted and left alone
5. Ran DiskUtils and chose to Repair the disk. I got a reasonable progress bar (as opposed the infinite one when I ran DiskUtils while Finder had stuff going on). It took over 12 hours to repair. Be patient!
6. Used the Mount icon in DiskUtils to mount Drobo.
7. All good, happy.
So now what? A backup of a backup on S3? Is there no end to this cycle?