Drobo 5D drives not visible in Win 11

Due to a crash and burn I have a new Win 11 computer. I have a Drobo 5D with five 4TB drives installed. Everything shows as good in the Dashboard. Both dashboard and firmware are current.

There are 3 virtual drives and none are visible to the File Explorer however the drives show in the Device Manager. I have tried to eject the Drobo but am told the device is in use. I’m looking for the “Damn Fool Operator Error” which is causing the problem.

Suggestions are welcome, gloating superiority accepted if you solve the problem.

Thanks / Glenn

Can you see them under ‘Disk Management’?

You may need to assign drive letters to each volume.

AzDragonLord – I do see them under Disk Management. They are connected through USB. I have discovered that the USB cable I am using is a 2.0 and not 3.0 and have a replacement cable on order.

I know how to change the system-assigned drive letter to assign a permanent drive letter to an existing device but that required the drive to be mounted in the first place. If it were a network drive I know how to map. I can’t find a way to assign a drive letter to a device which does not already have one.

Can you point me in a direction?

I also checked in with Support and they have a solution. The Drobo was previously attached to a Mac. As a result they are Mac formatted and cannot be read by a PC.

Choices are to lose the data and reformat or set up a Mac, move the data elsewhere and then reformat and move back. I’ll be checking with my Mac friends.

Thanks for the help. Hope this helps someone else.

Drive format makes total sense. Glad you found the issue.

You can try some software to read Mac drives on Windows. Something like this might work:


Won’t help long-term, but it could help you not need to chase down a Mac if you don’t have one handy.



Thanks for the thought. Drobo Support suggested HSF+ for Windows, by Paragon Software, and it worked perfectly. I was able to mount and empty the Drobo and am now using it on my PC. The software makes the Apple-formatted drive look like a NSF drive, so all the Windows software can see and interact with it. More powerful than I really needed but worked very well. The file transfer is slower than normal but it is not terrible. I was moving 3 TB around so anything is going to look slow.

Regards / Glenn