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

Reply
Question marked as Top-ranking reply

Posted on Nov 21, 2025 11:08 PM

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.

2 replies
Question marked as Top-ranking reply

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.

External Drive APFS Container Phantom Volumes

Welcome to Apple Support Community
A forum where Apple customers help each other with their products. Get started with your Apple Account.