Solving Drobo random unmounting issues

(Writing this up for hopeful discovery of future Drobo owners)

My Drobo started acting up a while ago in an incredibly frustrating way:

  1. The Drobo would sometimes not show up, or not mount, requiring a dance of restarting it, restarting the computer, plugging, unplugging
  2. When it was mounted, you’d get a short while before the Drobo went unresponsive in the middle of an operation, and then it’d unmount (and OS X would throw a warning about dismounting drives improperly)
  3. Sometimes if you left it connected for long enough, it would show up again, hang around for a bit, and then disconnect.

Nothing worked: re-installing software, resets, the “remove drives, reboot the Drobo, wait, turn it off, put the drives back in…” And all the while status-light-wise, and Drobo Dashboard-wise, it reported everything was good

And unhappily, Drobo support costs money, and I’m cheap, so I wasted a ton of time troubleshooting it. As a bonus, their error logging and messaging is either unhelpful or encrypted.

(I feel like if you encrypt your device’s logs, you should offer free support at least for unencrypting the logs and letting the user know what’s up. I’m disappointed in them and will not be purchasing future Drobos. Or recommending them.)

Eventually I pulled each of the drives and checked their SMART status (OK status overall on all drives, though I also pulled the details and one of them had flags, but SMART’s not great (see: Backblaze’s blogs on this). So I cloned them sector-by-sector onto identically-sized drives. The drive with the odd SMART errors (but, again, overall OK status) made some really unsettling noises at a couple points during sustained reads, but the copy went off okay.

Fired it up, and it worked. Drobo came back on, mounted, works fine (for nowwwww….).

I spent some more time hunting around in the Drobo support forums looking for more information, and found someone reporting back on a similar issue said they’d had a drive go bad but the Drobo never reported any issues, and it wasn’t identified until support looked through the encrypted error logs and said “oh, drive number X is going bad, that’s causing your Drobo’s strange behavior.” Clearly, given my success, at least one of my drives was secretly bad and cloning and replacing was the solution

So! May writing this up help at least one future support-stranded Drobo owner: if your Drobo is unmounting randomly, not showing up in the Finder, throwing dismount errors, but the Drobo’s reporting that everything is hunky-dory, and you don’t want to pay for support and you’re willing to take advice from some random fellow owner on the Internet who may not even have the same issue… here’s one approach before you throw your malfunctioning Drobo out the window:

  1. Power it down and pull the drives
  2. Using whatever utility you like, check the high-level SMART status on the drives to see if something’s clearly screwed up
  3. (optional, if they’re all okay) look at the detailed SMART errors and see if any of the drives looks really wonky
  4. If any of them are bad, do a sector-by-sector clone of that drive, swap the clone in, power up the Drobo, see if that works. If yes: yay! If not —
  5. Clone & replace them all, see if that works.

May this work, and may the drive be in good enough shape to successfully clone.

I should also note that as much as I’m annoyed my Drobo was out of support, assuming they would have been able to tell me what was happening and which drive to clone and replace, it would have been worth it to pay for the per-incident to save myself the headache.

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