I'm having some trouble getting a bootable backup for Big Sur working. I had one working fine with Catalina. Carbon Copy Cloner seems to report that the APFS replication procedure failed. One question I have is related to first attached screenshot; I am unfamiliar with this snapshot partition, could that be causing a problem? (For anyone that may come across this post in the future, Ars Technica has a good article in their Big Sur review about how this works) I don't see the normal system and data volumes so I figured I would bring it up. The second screenshot is what I get when I try to run first aid in disk utility. With these problems, and the lack of a bootable backup due to Carbon Copy Cloner deleting my Catalina one, I'm a bit nervous. Any advice on how I should proceed? I haven't had any issues with Big Sur.
@jlr
I'm not sure what you mean by "I haven't had any issues with Big Sur." But here's an approach based on what I think you mean.
Be sure you have the latest version of Carbon Copy Cloner. Your "Container disk3" is what is typically displayed in Disk Utility because of Apple's "Secured System Volume."
I don't know why you are getting a Disk Utility error. You should get YOUR data backed up ASAP to another drive making a full Time Machine backup. It looks like you may need to reformat the Samsung 970 EVO and reinstall a new macOS system and restore your data to be sure you get the error corrected.
You should fix the problem with the Samsung 970 EVO before you try to make any CCC backups or clones from it.
I make full bootable backups of Big Sur and Monterey Betas all the time with CCC. The "trick", at least for me, is to ERASE the drive (in your case "Big Sur Local Backup") in the Container you are going to use for the bootable backup first. Otherwise if you try to use the CCC "APFS Replication" feature it may or may not simply report a failure when it starts to run the Task to make the clone.
For example, if you are trying to make your bootable backup to "Big Sur Local Backup," you need to use Disk Utility to select "Big Sur Local Backup" and Erase it.
Then in CCC select "Big Sur Local Backup" as the destination drive. Then select the "APFS Replication" selection in the popup list and in the dialog that is displayed select the option to let CCC (once again) erase the "Big Sur Local Backup" drive. Start the clone operation and all should proceed normally. (At least from my experience.)
In subsequent backups to the backup drive, CCC will only copy your changed data because the System is "secured" and none of its contents should have been modified.
For example, if you had updated the Big Sur version in your working source disk, the next time you run the CCC Task to clone the source drive, only your data is cloned. The prior Big Sur version files will not be cloned.
You also
may need to install the appropriate EFI folder on the newly bootable backup drive for OpenCore to use to boot.
This has worked for me to make bootable backup drives on both internal and external drives.
Another option was also suggested where you use CCC to clone all your data to a drive, then use a Big Sur or Monterey installer to install the system on that drive to make it bootable.
BE VERY CAREFUL SO YOU DON'T LOOSE YOUR DATA! Always have your data backed up on another drive that you are sure contains everything you need.