Some backup volumes don't appear in the Finder sidebar
If you created a bootable copy of Catalina or Big Sur in the past, and then proceed with CCC backups to that volume on Monterey without specifically using the Legacy Bootable Copy Assistant, CCC will remove the incompatible System volume from the destination. The remaining Data volume appears just fine on the Finder Desktop, and also in the volume list when you select "Computer" from the Finder's Go menu. The Finder sidebar, however, will not show these volumes, regardless of your Finder preferences to show external volumes in the sidebar, and regardless of any attempts to drag the volume explicitly into the sidebar.
We have reported this issue to Apple (FB9739492) and we are currently awaiting a response.
Workaround: Choose "Computer" from the Finder's Go menu to see your destination volume in the Finder.
Apple's SMB filesystem client causes system stalls, random application crashes, and may lead to kernel panics
Update (macOS 12.3): This issue appears to be effectively resolved in macOS 12.3.
We have received several reports from Apple Silicon Mac users of unruly macOS behavior that occurs while copying files to an SMB-mounted NAS volume. The behavior includes the following:
- Random application crashes
- Prompts to grant various macOS system services access to the login keychain (i.e. because the service that retains the unlocked keychain reference crashed, thus locking the keychain)
- Laggy mouse behavior
- System stalls that eventually end with a reboot and kernel panic report
We were able to reproduce this behavior using a simple shell script that creates files and folders on SMB-mounted NAS volumes (and also with Finder copies). The underlying problem appears to be a memory leak in the macOS kernel or one of the kernel extensions. Specifically, the "kext.kalloc.32768" memory zone is expanded until it can no longer be expanded ("zone_map_exhaustion" occurs), at which point the memoryd system process starts to terminate idle processes. This problem is limited to Apple Silicon Macs and SMB volumes.
We reported this issue to Apple in January 2022 (FB9857268). Apple indicated that they had made significant progress on this issue in the 12.3 update. We're still able to reproduce high memory pressure, however we're no longer seeing the complete memory zone exhaustion that was leading to kernel panics. Likewise, we haven't received any additional reports of this issue from any 12.3 users.
Workaround: We have confirmed that using AFP rather than SMB consistently avoids these behaviors (in cases where using AFP is an option):
- Eject the NAS volume if it's currently mounted
- Open CCC and select the applicable backup task
- Click on the Source or Destination selector (whichever is applicable for your particular task)
- Hold down the Option key and choose "Switch to AFP" (provide the credentials for the NAS volume again if prompted)
- Save and run the task
While we recommend using AFP whenever it is an available option, it's important to note that AFP is a deprecated protocol and that some NAS vendors have started to drop support for it (e.g. Western Digital MyCloud). If you are not happy with the performance and reliability of Apple's SMB filesystem client on the latest version of maCOS, please share that feedback with Apple, and please feel free to include our FB9857268 bug report number in that feedback.
CCC will not update the System volume on a Legacy bootable copy of the startup disk (Big Sur and later)
Starting in macOS Big Sur, the system now resides on a cryptographically sealed "Signed System Volume". That volume can only be copied using Apple's proprietary APFS replication utility ("ASR"). Right now, ASR will only copy whole volume groups (System and Data); we can't choose to copy just the System volume. As a result, every time an OS update is applied to the source, you would have to erase the whole destination volume (including any existing snapshots on that volume) just to update the system on the destination. We made a feature request to Apple in September 2019 (FB7328230) to allow ASR to clone just the System volume. We do not anticipate that Apple will implement our requested functionality.
To avoid deleting your snapshots and the rest of your backup, CCC will not update the System volume on the destination when System updates are applied to the source.
Our recommendation: We recommend erasing the destination only when you have an immediate need for a bootable copy of the system (e.g. if you're migrating to a different disk, or creating a copy of the system for testing purposes). A Standard Backup is simpler and more appropriate for establishing a robust, long-term backup strategy.
Workaround: Any time you want to make the OS on the destination identical to the source, simply click on the Destination selector and choose Legacy Bootable Backup Assistant... to configure CCC to re-erase and reclone the entire volume.
Finder will not show, nor allow you to set custom icons on other Catalina, Big Sur or Monterey startup volumes
Finder will show and allow you to customize the volume icon for your current startup disk, but not for other Catalina+ startup volumes that your Mac is not currently booted from. This problem is not specific to CCC backups, but we see this frequently because CCC can create copies of macOS System volumes. This problem is the result of a design flaw in the implementation of custom icons in an APFS volume group. Up to macOS Catalina, the custom volume icon is stored in a file at the root of the startup disk named ".VolumeIcon.icns". To keep the System volume read-only, yet allow the apparent modification of this icon file, Apple chose to create a symbolic link at the root of the startup disk that points to System/Volumes/Data/.VolumeIcon.icns. For the current startup disk, this path resolves correctly because the Data member of the volume group is mounted at /System/Volumes/Data. That's not the case for external volumes, those Data volumes are mounted at /Volumes/CCC Backup - Data (for example). As a result, the symbolic link to .VolumeIcon.icns is unresolvable for any volume that is not the current startup disk.
We reported this issue to Apple in May 2020 (FB7697349) and we are still awaiting a response.
Alternative: We recommend creating "Standard" backups instead of creating a legacy bootable backup. Finder will issue no challenges to customizing the icon of a volume with a Standard Backup.
Finder will let you rename the current startup disk, but you won't be able to rename any other startup disks that have an installation of Catalina, Big Sur or Monterey because the System volume is mounted read-only.
We reported this issue to Apple in November 2020 (FB8912480) and we are still awaiting a response.
Solution: Unmount and remount the volume in Disk Utility, then right-click on the volume in Disk Utility's sidebar and choose the option to rename the volume.