macOS uses snapshot IDs to protect Time Machine data, which prevents Disk Utility from partitioning or erasing volumes directly. The most reliable workaround is to use the Terminal command line with diskutil apfs list to identify snapshots and diskutil apfs deleteSnapshot to remove them before performing any partitioning operations.
The Snapshot Protection Mechanism
Modern versions of macOS, particularly those running on Apple Silicon and recent Intel-based Macs, utilize the APFS file system extensively. A core feature of APFS is the ability to create instantaneous snapshots of a volume. These snapshots are primarily designed to support Time Machine backups and local time travel features. When a snapshot exists on a volume, the operating system places a lock on that volume to ensure data integrity during backup processes.
This protection mechanism creates a significant hurdle for users attempting to modify drive structures. If you attempt to erase, resize, or repartition a volume that has an active snapshot through the standard graphical interface, Disk Utility will typically fail. It may report that the operation cannot be completed because the volume is in use or protected. This behavior is intentional by Apple to prevent accidental data loss during critical backup windows. Understanding this underlying protection is the first step toward resolving the issue without losing your backup history.
Identifying Active Snapshots via Terminal
While Disk Utility provides a visual overview, it often hides the technical details of snapshots. To work around these restrictions effectively, you must use the command line tool known as diskutil. This utility offers granular control over APFS containers and volumes that the GUI does not expose. Open the Terminal application, which you can find in the Utilities folder within Applications.
Begin by listing all APFS containers and their associated volumes. Run the following command in your terminal:
diskutil apfs listThis command outputs a hierarchical view of your disk structure. Look for the section labeled "APFS Volume." Inside each volume entry, you will see a field named "Snapshots." If this field contains a number greater than zero, or lists specific snapshot identifiers, that volume is locked. Note the identifier of the volume you wish to partition, such as disk1s2, as you will need it for the next steps. This diagnostic step confirms whether snapshots are indeed the cause of your partitioning failure.
Removing Snapshots to Enable Partitioning
Once you have identified the volume with active snapshots, you must remove them to unlock the volume for modification. You can do this safely using the deleteSnapshot command. However, before proceeding, ensure you have a current backup if possible, although deleting local snapshots generally does not affect your Time Machine cloud or external backups.
To remove a specific snapshot, use the following syntax:
diskutil apfs deleteSnapshot [VolumeIdentifier] [SnapshotID]For example, if your volume is disk1s2 and the snapshot ID is 5A3B...9C2D, the command would look like this:
diskutil apfs deleteSnapshot disk1s2 5A3B...9C2DIf you wish to remove all snapshots from a volume at once, some users prefer to reboot into Recovery Mode. In Recovery Mode, you can sometimes bypass certain locks more easily. However, the Terminal method is often sufficient for standard user-level snapshots. After deleting the snapshots, run diskutil apfs list again to verify that the snapshot count has dropped to zero. Once the count is zero, return to Disk Utility.
Partitioning the Drive
With the snapshots removed, the volume should now be available for modification. Open Disk Utility and select the drive or container you intend to partition. Click the Partition button in the toolbar. You can now adjust the partition map, add new volumes, or resize existing ones without encountering the previous errors. Apply the changes and wait for the process to complete.
If you encounter persistent issues after removing snapshots, consider checking for other potential blockers. Sometimes, third-party security software or mounted network drives can interfere with partitioning operations. Ensure no external drives are connected and no network shares are mounted on the target volume. For more complex APFS errors, you might also refer to guides on handling record errors during erasure, such as those found in our article on Erasing 'doc-id' Record on APFS Disk (macOS Monterey).
Recreating Snapshots
After you have successfully partitioned your drive, you may want to restore the snapshot functionality for future backups. macOS typically recreates local snapshots automatically when Time Machine runs or when you perform certain system updates. You do not need to manually recreate them. Simply allow Time Machine to perform its next scheduled backup, and the system will generate new snapshots as needed. This ensures your drive remains protected against data loss while maintaining the flexibility to manage your storage layout.
Frequently Asked Questions
Can I delete snapshots without using the Terminal?
Standard versions of macOS do not provide a direct button in Disk Utility to delete individual snapshots. While newer versions of macOS Sonoma and later have introduced more management options in System Settings, the Terminal remains the most universal and reliable method for older versions and precise control.
Will deleting local snapshots affect my Time Machine backups?
No, deleting local snapshots does not delete your Time Machine backups stored on an external drive or in iCloud. Local snapshots are temporary copies used for recovery and versioning on the internal drive itself. Your historical backup data remains intact and accessible.
What should I do if Disk Utility still fails after removing snapshots?
If partitioning still fails, check for other locking mechanisms. Ensure that FileVault is fully decrypted or that you are not trying to partition the boot volume while it is heavily in use. Rebooting into Recovery Mode and trying the operation there can also bypass many runtime locks.
How do I know if a snapshot is causing the error?
Run diskutil apfs list and look at the "Snapshots" field under the volume you are trying to modify. If the number is greater than zero, snapshots are present. If the number is zero and you still get errors, the issue is likely related to filesystem corruption or other hardware issues rather than snapshot locks.
Is it safe to force-delete snapshots if I am unsure?
It is generally safe to delete local APFS snapshots as they are redundant copies. However, always ensure you have a valid backup before making structural changes to your drive. Deleting snapshots frees up space but does not replace the need for a comprehensive backup strategy.