Can't mount 14TB External USB drives in Sonoma OS 14.3.1

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Can't mount 14TB External USB drives in Sonoma OS 14.3.1

Using an Intel 2020 iMac. I purchased 3 Seagate Expansion USB drives that are 14TB for backing up. They are formatted ExFat. When I first copied data to the drive they mounted. Then on next reboot, they are grayed out in DiskUtil. They do not mount and produce this error when I click mount in DiskUtil. Could not mount “DriveA”. (com.apple.DiskManagement.disenter error 53249.)

I reformatted the drive and same error. I tried a second drive. Same error.

In Terminal

diskutil list external

/dev/disk10 (external, physical):

#: TYPE NAME SIZE IDENTIFIER

0: GUID_partition_scheme *14.0 TB disk10

1: EFI EFI 209.7 MB disk10s1

2: Microsoft Basic Data DriveA 14.0 TB disk10s2

diskutil mount readOnly disk10

Volume on disk10 failed to mount

If it has a partitioning scheme, use "diskutil mountDisk"

If you think the volume is supported but damaged, try the "readOnly" option

diskutil mount readOnly disk10s2

Volume on disk10s2 failed to mount

If you think the volume is supported but damaged, try the "readOnly" option

Tried on my MacBook Pro Ventura 13 - Same thing.

But out of the box, the drives both worked until I copied 5 TB over from another external and rebooted.

Posted on Mar 8, 2024 6:27 AM

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Answer 1

Dave Beaty Author

Level 1

5 points

Mar 9, 2024 11:32 AM in response to Owl-53

No. As I said I have a few new Seagates. When I connect to Mac they mount. If I copy data to them and reboot they no longer mount. When I run DiskUtil they showup but will not mount producing an error. Disk first aid results in no errors found.

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Answer 2

Dave Beaty Author

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5 points

Mar 8, 2024 9:38 AM in response to Dave Beaty

I am not sure how to proceed. I can reformat the external, but want to use it in a PC environment. I don't recall ever having an issue with other external drives, such as the smaller ExFat 2TB variety. These are the first 14 TB externals I've used.

The one I formatted to the Mac file system works fine so it's def ExFat. And when I first plugged in the drive it showed up as "Expansion" with the Seagate factory format ExFat and read write normally. Only after copying data to it and rebooting did it disappear and result in the error and problem mounting. Then even after a reformatting it will not show up as ExFat.

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Answer 3

Owl-53

Level 10

97,825 points

Mar 8, 2024 10:01 AM in response to Dave Beaty

This may involved purchasing Third Party Disk Management software that can Read and Write to the Native NTFS Drive format of MS Windows format

It would required that this software be compatible with macOS and run on the Apple Computer

I know of such software but do not use myself as all my computing is done Solely on Apple Computers

It is understood, if going this route will require the drives be reformatted on MS Windows in the NTFS format

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Answer 4

Owl-53

Level 10

97,825 points

Mar 9, 2024 12:59 PM in response to Dave Beaty

" Volume Type " >> " Unknown "

This is from your above image

To me, that explains the problems

As to Why the exFat Partition Map is not holding - I do not know

Has I have seen mentioned, on thee Forums, some newer WD and Seagate drives are manufactured with inferior parts

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Answer 5

Owl-53

Level 10

97,825 points

Mar 8, 2024 7:24 AM in response to Dave Beaty

From another good posting from @HWTech for important info regarding exFat drives on macOS

Issues with external drives and macOs Son… - Apple Community

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Answer 6

Owl-53

Level 10

97,825 points

Mar 8, 2024 7:28 AM in response to Dave Beaty

Follow on " Sonoma OS 14.3.1 "

Current version is now version 14.4

About the security content of macOS Sonoma 14.4

Always make a Time Machine Backup before doing any upDates

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Answer 7

Mar 26, 2024 4:54 PM in response to Dave Beaty

Have you seen this post - Unable to access External Drives and Disk Utility after updating to macOS Sonoma? Seems related to Sonoma where they changed exFAT to a user space driver.

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Answer 8

Dave Beaty Author

Level 1

5 points

Mar 8, 2024 10:20 AM in response to Owl-53

That is a viable route. I have also used MacDrive successfully on the PC system reading AFS. I am perplexed at this seeming failure on the Macintosh side.

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