After Big Sur update, I can't mount my Drobo...

Use the USB 3.0 cable to USB A type (then C type) to connect to your Mac with Big Sur. Just used the old cable that came with my 5D (had to dust it off), and it works and Drobo is now accessible and working. I have also reached out to Drobo to ask them when Big Sur with thunderbolt will work, but in the interim this works...Good luck!

Yay! Thanks for the update!

Downloaded Dashboard (which does not show version number in the filename). Still says 3.5.1 on the website as of this moment. Download it anyhow.

Uninstalled Drobo Dashboard 3.5.1.

Installed 3.5.2 and my 5D's now mount and are seen in Dashboard.

Drobo have confirmed that Release Candidate 2 of macOS 11 broke Thunderbolt compatibility with the Drobo. Unfortunately, RC2 is what we're all installing via Software Update so...

You can access the drive using the USB3 interface, but it will not appear on the desktop and people report that it is unstable (it crashes Finder a fair bit).

Drobo is working with Apple to address this. Evidently there was similar issue when Catalina first dropped, as well.

https://myproducts.drobo.com/retrieve/s3/knowledge/AA/Frequently%20Asked%20Questions:.html

I've downloaded this file and can also confirm it has restored connectivity :)

Just FYI I had to completely uninstall the existing dashboard first before installing the 3.5.2 update (using the uninstall function on the 3.5.2 dmg) - just installing over the top did not work for me originally.

OK back to normal finally!

Edit: Full Disk Access

Took me a couple of tries but finally worked, following Drobo's support doc. You have to completely uninstall your current Drobo Dashboard using the uninstaller file (Library>Application Support>Data Robotics). Disconnect Thunderbolt cable from Drobo unit. Install latest version (3.5.2). Shutdown your computer. Reconnect Thunderbolt cable. Then restart your Mac. After two tries, worked for me.

https://myproducts.drobo.com/retrieve/s3/knowledge/AA/Frequently%20Asked%20Questions:.html

Yes. One link away. I have a 5D so I went to the 5D link https://www.drobo.com/docs/start-5d/

According to the Macrumours forum the public beta 11.1 release fixes the issue (scroll to the bottom of the following link)

https://forums.macrumors.com/threads/big-sur-w-drobo-thunderbolt-not-working.2267890/

Not long to wait for the main general release now hopefully.

well, I had to erase and factory reset my Drobo to get it working again after not hearing back from Drobo support for 5 days. Now it works like new. Just waiting on my 2 TB worth of files from backblaze. Thanks to everyone here for your help.

I can confirm that Drobo Dashboard 3.5.2, downloaded from the link here, fixes the problem.

Drobo, not Apple, are responsible for their product compatibility with the officially released Big Sur. Drobo will have to release an update for Big Sur to resolve this issue.

It's disingenuous for Drobo to say they are "working with Apple". They may not be lying if you call 'looking at documentation to see what we missed' - working with Apple. By comparison, I have a Promise Pegasus32 drive and prior to the Big Sur release they pushed out an update to their app that made the drive compatible with Thunderbolt changes in Big Sur.

I went through most of the work arounds and hoop jumping in this thread so I don't know for sure what part of which one of these got it done, though I suspect it may have been noah501, but it was switching from thunderbolt to USB3 that did it. I'll see how long it holds out before the crashing begins and report back my experiences here.

Then you need to ask Drobo support.

I've had so many Drobo problems including times when all drives go red and I've had to initialize and copy all the data back. So yes, when nothing else works, I guess rebuilding the array is all you can do. I've had similar issues occur for no apparent reason, in what I would consider a hardware failure. This happened another time after a power outage during nighttime where I think it was doing a scheduled backup while the UPS ran out. One time I was able to get it all fixed by some series of removing one drive and restarting it. I don't recall exactly the sequence of events. But I assume Drobo support had you try that.

BTW... This is why I've moved on to Pegasus32 drives. I'm holding onto 2 Drobo's as backups to my 2 Pegasus32 drives. I no longer can count on Drobo.

Understanding my problem was quite different than yours, it sounds like you followed my steps just to see if a clean uninstall, reinstall helps you? And it did not. It didn't cause any change in behavior other than the OS now recognizing that something is wrong with the drive. And maybe that's a good thing. Curious, when you uninstalled dashboard, did you use the disk image's Uninstall option? Hopefully so.

Sorry for all the rambling above. I'm no expert and instead I just tinker with crap until I'm lucky. Understanding that, here's what I would do: Another unplug drive, uninstall DD, remove all residual files you can find (incl. .kext). But then one more thing... I would also move 2 drives in the Drobo unit before I reconnect it. This should make it look and feel like a new Drobo and therefore I would expect the Dashboard to walk your through how to build a new array. But - I'm no expert and you're in uncharted territory. You may instead prefer to just try the initialize as you suggested. Good luck.