Drobo 5c Mac (Catalina) random ejects - any solution?


There are a number of elderly threads on this, so I was wondering if there is any fix to the problem of my Drobo 5c randomly ejecting when my Mac is left alone for a while?

I come back to dozens of ‘Disk not ejected properly messages’ and the device (called Drobo) now appears in /Volumes as Drobo, Drobo 1, Drobo 2… Each time it is disconnected, the disk appears to mount normally shortly afterwards - it is visible in Drobo Dashboard and I can browse it in Finder. However, my Backblaze backup which is looking for a disk called Drobo now sees a disk called Drobo 1 which remains until I restart either the Drobo or the Mac.

The Mac is a new iMac Pro running macOS Catalina 10.15.5. The Drobo is running firmware 4.1.4 [11.66.111430] and Drobo Dashboard is Version 3.5.0 [113780].

The Drobo is directly connected to the Mac using the supplied cable to the iMac’s Thunderbolt ports and is using the normal power supply.

The Mac’s energy saving features are set with ‘Prevent computer from sleeping automatically when the display is off’ [OFF]; ‘Put hard disks to sleep when possible’ [OFF]; ‘Wake for network access’ [ON]; ‘Start up automatically after a power failure’ [OFF]; and ‘Enable Power Nap’ [ON].

‘Disk Drive Spindown’ in Drobo Dashboard’s General Settings is [OFF].

Drobo Dashboard cannot see any problems with the Drobo or the disks (all lights are green and there are no errors). I have checked with macOS Disk Utility and used First Aid - no errors were found.

So I’m baffled - annoyed and baffled. Am I missing something and there is a nice easy solution; or is this still a mystery?

Many thanks.


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“Nice easy solution”"
Switch to Windows.

Most of the threads with no solution are either hardware (disk or Drobo itself), or Macs… Just sayin.

Sounds like mine:

Only solution I’ve found so far is not to let the Mac sleep. which … isn’t great.

Thanks for that suggestion - as you say, it’s not great. It’d be nice to know if it is the Mac or the Drobo which is the root cause of the problem.

Appreciate you taking the time.


Agreed – surprised there aren’t more people with this problem. Might have to look at DroboCare if there aren’t enough others to make progress.

I was just about to post the same question. You’re describing my issue exactly and I have the same setup (except it’s a MacBook Pro). This was happening before I upgraded to Catalina and the new Drobo firmware, so (for me at least), it’s not that.

What kind of drives are you using? I’m running 6/2/2/3/4 TB Seagate BarraCuda drives. Possibly an issue there?

This is rendering the unit basically worthless.

I’m using a mix of 2 and 4TB Seagate Iron Wolf NAS drives if it is any help.

The issue is so serious I’ve started migrating critical data to a Synology NAS because I’m terrified the Drobo will trash something critical.

Let’s hope there is a fix soon.

I’ve been given the same suggestion. Which is a real bummer with over $1,000 invested in the unit. Since I’m using BarraCudas, I won’t be able to recycle those over to a Synology - so I’ll be starting over from scratch.

My unit just diagnosed one of my drives as critical. I’ve had this disconnect issue for months, so I can’t imagine the problems are related, but at this point who knows.

I’m going to open a customer service request with Drobo even though I hate to throw good money after bad. If I get a solution, I’ll post it.

Good luck with a customer service issue. A dig through Google, Apple support and Reddit suggests this a long-standing issue that no one seems to understand (it might also affect some LaCie USB drives). I’ve had it on several Macs running different versions of macOS and different hardware and it just doesn’t go away.

Fingers crossed - because as you say, these devices and the drives are not cheap.

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Have to admit, I’ve been considering moving to a Synology NAS for a while; the cost of buying a new unit while keeping this one running has made that less appealing, but if I can’t fix this issue …

Hope you’re able to find some useful information via DroboCare.

My mix of drives is varied – partly because I started with 3TB Barracudas that had a high failure rate, and lost a bunch in the first year or two, so I got paranoid about having too many drives of the same model, even though that’s often considered a good thing for RAID.

Oh, Good, Drobo Dashboard isn’t showing my unit at the moment, so I can’t list the drives. How nice to see. I’ll report the drives later. I know a few of them are IronWolf, but I think there’s a WD Red in there as well, and the capacities vary.

3x 8TB IronWolf
2x 4GB WD Red

I’m going to open a customer service request with Drobo even though I hate to throw good money after bad. If I get a solution, I’ll post it.

Any luck?

Hi, My suggestion would be to use USB-c if your Drobo supports it. The speed difference is not that great, if any, but that is a separate issue. I’m a beta tester for Apple (not an employee) and I can state that this is much less of an issue with Big Sur and my Drobo 5D3. I have it connected to Thunderbolt 3 and it hasn’t disconnected yet, on Beta 3. However, many Drobo users are reporting that their Mac doesn’t even see the Drobo using Thunderbolt 3.

My personal opinion is that it is an issue with the Drobo Thunderbolt drivers. Hopefully when Big Sur releases this fall and Drobo updates their Dashboard and firmware the issue will be resolved.

My suggestion would be to use USB-c if your Drobo supports it.

I mean, it does and it doesn’t. I have a 5D, so it has a USB 3.1 SS port on the back. I’m currently connected from a Mac mini USB-C port to the USB 3.1 SS port using a SS/C cable, no dongles. So – the Drobo doesn’t support USB-C, but I’m using a USB C port to connect.

My personal opinion is that it is an issue with the Drobo Thunderbolt drivers. Hopefully when Big Sur releases this fall and Drobo updates their Dashboard and firmware the issue will be resolved.

I’m guessing that because I’m using the USB connector on the Drobo side, this isn’t a Thunderbolt driver issue, but because the Thunderbolt port and USB-C ports are basically the same on the Mini side, I can’t swear to it; I don’t know enough about the driver internals of MacOS to argue. In any case, if Big Sur helps, I’ll look forward to that.

I could try connecting via Thunderbolt, but I’d have to get a Thunderbolt 2-3 adaptor, which isn’t cheap, and lots of people seem to have this problem WHILE using Thunderbolt, so I’m not super-excited about shelling out for an $80 adaptor if it doesn’t solve the problem. :wink:

I could also be the cable. Make sure the cable is certified for data. There are a lot of cables out there that are designed for just charging and not data. It might be worth ordering the Thunderbolt adapter and if it doesn’t work, return it for your money back. Amazon, Apple and B&H Photo all have excellent return policies.

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Sorry for the delayed response - I’m not sure if this will prove helpful… I ended up getting a Synology NAS and love it so far. Right about the time I was fooling with this, the Drobo reported a drive failure. It was a 4tb BarraCuda, about 2 yrs old. The failure freaked me out so I decided to quit messing with it and just buy the Synology. I took out the bad drive, let the Drobo do its re-sorting and then when I went to transfer stuff from the Drobo to the Synology, it performed just fine. No dropping off or anything…

I don’t know what to make of this. It was dropping off frequently long before the drive was flagged by the Drobo, but maybe there was a problem? After the drive was removed, it began working fine. The biggest problem I had was when transferring Blackmagic RAW video files - typically 5gb and up. It would get partway and just drop.

I wish this was more enlightening.

same issue here first on 2019 MacPro and now on brand new iMac 5k 2020.

I’m in the process of selling all my Drobo’s (I have 5) and moving to OWC Thunderbolt 3

I did month of trouble shooting with every possible setting, replacing supposedly not good drives, installing utilities which prevent HD’s going to sleep all to no avail. Even got rid of my MacPro and changed for a new 2020 5k iMac still same issue. So all my 5 Drobo’s are on ebay now. Drobo support is pretty much useless!

Screen Shot 2020-09-01 at 8.12.00 am|144x500

Replacing the cable I was using with the USB-C that came with my MacBook Pro seems to have fixed the eject problem I was having on new 5K iMac Catalina. Stays mounted and works fine on 5K iMac (Catalina) now EXCEPT Drobo Dashboard does not see it. Everything fine on MacBook Pro on earlier system.

Bit of an old thread but wanted to mention I’m having the same problem with a 5D (thunderbolt 2) on Big Sur.

Drobo just started randomly cutting out since I installed the latest firmware and dashboard they released to allow thunderbolt to work correctly on Big Sur.

I’m not sure if its entirely related but I contacted support and got a quick response that the drives in bays 1 and 2 were both showing a warning. No lights indicated this but if I went into the dashboard I could see it.

The drives were nearly 10 years old so figuring I was dicing with death I went and bought 4 new ironwolf drives. The issue seemed to go away for 1 day then came straight back. Interestingly the same 2 bays are now showing a warning.

I’m wondering if there is a lose connection in the Drobo unit that is causing those drives to sometimes lose power. When this happens the Drobo is panicking and rebooting. Luckily I think I have all the data now off onto another drive. However there are no Drobo’s for sale anywhere, but it sounds like moving to a Synology will be the way forward and will fit better into my workflow anyway.

If I can get the drives to at least finish the data protection mode I’m going to boot down and check whether there is anything obvious, maybe some dirt or something where the drives go in. Worst case if I brake the Drobo I’ve not lost anything

Still an old thread but an ongoing problem. Been looking for possible solutions to this off and on for a year plus. So, my situation is a bit unusual in that I have an older iMac (Late 2013) that has a Drobo 5D and I can honestly say I have NEVER had this problem with unexpected ejects. I also have an older MacMini (Late 2012) that has the same Drobo 5D which I use to (try to) host my media server. Since well before Catalina we’ve been plagued with the mini constantly “unexpectedly ejecting” the Drobo, hence making it’s usefulness as a media server poor. Both macs have the same Catalina upgrade - and neither can use Big Sur, so can’t speak to that issue. The only difference I can really say about the two Drobos are the drives that are in them. The “clean op” Drobo has simply 5 4TB Seagates (Greens I think) and the mini has a combo of 3 6TB WDs and 2 3TB WDs. I’m sure I looked at some drive compatibility chart for drobo in the distant past and at the time these were appropriate drives for the unit.

Not sure I’m ready to plunk down on a bet that seagate are somehow immune to this effect but there are my two cents if anyone has had a similar experience or can debunk the “seagate immunity” hypothesis.