External Drive APFS Container Phantom Volumes

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Al Hatch Author

Level 2

235 points

External Drive APFS Container Phantom Volumes

External APFS drive A is formatted with just 1 Container. The container’s 2 mounted volumes appear on the desktop. However, Disk Utility shows “SHARED BY 5 VOLUMES” and “3 Not Mounted”. Moreover, it shows that the “3 Not Mounted” account for 483.3MB.
External APFS drive B is formatted with just 1 Container. The container’s 3 mounted volumes appear on the desktop. However, Disk Utility shows “SHARED BY 6 VOLUMES” and “3 Not Mounted”. Moreover, it shows that the “3 Not Mounted” account for 856.0MB.

What are these phantom volumes? How do I remove them to get the drive space back?

NOTE: This is NOT my internal startup drive.

Mac Studio (2022)

Posted on Nov 21, 2025 10:06 PM

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Answer 1

Top-ranking reply

azaksalmarzur28

Level 2

426 points

Nov 21, 2025 11:08 PM in response to Al Hatch

The “3 Not Mounted” volumes you see on external APFS drives are normal APFS system/metadata or snapshot volumes. They share container space and appear in Disk Utility but not on the Desktop. You usually cannot and should not delete them individually. To reclaim space, either remove local snapshots or fully reformat the drive to reset the container. These phantom volumes are part of APFS’s dynamic storage design, not wasted or corrupted space.

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Answer 2

Al Hatch Author

Level 2

235 points

Nov 21, 2025 11:15 PM in response to azaksalmarzur28

Thanks for the explanation.

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Answer 3

Al Hatch Author

Level 2

235 points

Nov 23, 2025 11:04 PM in response to HWTech

Thanks. I will run these in the next day or so.

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Answer 4

HWTech

Level 9

68,432 points

Nov 23, 2025 4:51 PM in response to Al Hatch

Disconnect all external drives.

Connect one & only one of your external drives & run the following Terminal commands & post the results here so we can see the actual drive layouts.

diskutil  list  external

And this one which will show all of the APFS volumes on that one connected drive (copy & paste this command since it is a bit complex):

diskutil ap list "$(diskutil list external | awk '/APFS Container Scheme/ {print $NF}')"

After getting the results for the first drive, disconnect the first drive. Connect the second drive & run both commands again to get the details for the second drive.

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