External drive problem on Tahoe 26.1

Question

Level 1

0 points

External drive problem on Tahoe 26.1

M4 iMac, macOS Tahoe 26.2

Western Digital Elements 4 gb USB drive with 2 partitions: one MacOS Extended (journaled); one Fat 32

I just backed up a bunch of files to the Mac partition, and the drive is behaving strangely.

The Mac volume could not be ejected. After disconnecting the drive and reconnecting, the Fat partition no longer mounts. The Mac partition does mount and I can open files. The Mac volume still can’t be ejected.

When I attach the drive to a Windows PC, the Fat volume mounts and works fine.

When this drive is connected to the Mac, Disk Utility shows no devices, not even the boot drive. View is set to show all devices but device and volume lists are empty. With this drive disconnected, the boot drive and other USB drives appear as normal

Running “diskutil list” in Terminal does nothing when the drive is attached - does not return to command line.

I have two other external drives, and both work fine.

I have restarted the iMac several times to no avail. Also tried different cables.

Any ideas? Is there a way to get to my Fat volume on the Mac? Right now there isn't even a way to reformat the drive. How can I do this?

Thanks.

iMac (M4, 2024)

Posted on Nov 21, 2025 6:57 AM

Reply

Answer 1

steve626

Level 6

13,623 points

Nov 21, 2025 7:15 AM in response to Bill Hole

Have you tried those things while booted into Safe Mode?

The lack of responses from Disk Utility or from diskutil/Terminal and the other issues you report are consistent with the Mac having a problem accessing the drive; when that happens, Disk Utility (or diskutil) simply produce no response. Certain file catalog items need to be accessible for a Mac to be able to utilize the drive and it appears to have been damaged such that the Mac cannot use the file system anymore. A PC is different and might still work even if the Mac does not. The Mac problem can be caused by either physical damage or an unexpected change to the file catalog.

Also, are you using WD's proprietary disk tool software/firmware? If so, it would have to have been updated to ensure it is compatible with Tahoe BEFORE updating to Tahoe and that could also cause inability to access the drive from the Mac side. Other problematic items include antivirus, "cleaner" type programs (CleanMyMac and other similar items), third party security tools.

Reply

Answer 2

Bill Hole Author

Level 1

0 points

Nov 21, 2025 5:01 PM in response to steve626

Thanks for that info. As it turned out, I got started on other tasks after my last attempt to eject the drive, and after about 20 minutes I noticed that it had unmounted. I remounted and now it's working fine.

I'm not using the proprietary WD software, so that's not the issue. I've had the drive for years and it's probably showing its age. I think it's time to replace it.

Reply