Carbon Copy Cloner: can I restore from a previous backup using Setup Assistant/Migration Assistant?

[Brian33]

Thanks for the input, @Ben J. !

That means you can select a snapshot in DU and choose to restore it to an already existing " - Data" volume. You'll get all the user accounts, of course, but you can delete unwanted users later. (You'll have to use DU from restore partition, or another boot disk, of course.)

I had not considered using Disk Utility to do the restore, as I've never done that before. Sounds like a good option. I assume this would be done from Recovery.

Within DU, apparently you select the destination volume first, and click Restore, and then select a backup snapshot? I tried this with my external (non-boot) volume (to avoid in-use boot volume complications). However, I'm unable to select a backup snapshot to restore from, even if it is currently mounted. The "Restore From" dropdown only shows volumes, and no snapshots. What am I doing wrong?

My prime CCC backup drive is bootable

So you use CCC's "legacy bootable backup" feature for that? I was somewhat convinced (by Bombich's own documentation) that doing so was unnecessary and not recommended anymore.

so I would boot from there and use CCC to restore from snapshot to the desired " - Data" volume

Yes, that seems like it would work well, assuming the System volume does not need to be restored (that is, there's been no macOS update to "undo").

(A very nice thing with doing it this way is that CCC will just restore the files that are changed or deleted since the snapshots, so, often it takes seconds.)

A very good point!

 

[Ben J.]

I had not considered using Disk Utility to do the restore, as I've never done that before. Sounds like a good option. I assume this would be done from Recovery.

Within DU, apparently you select the destination volume first, and click Restore, and then select a backup snapshot? I tried this with my external (non-boot) volume (to avoid in-use boot volume complications). However, I'm unable to select a backup snapshot to restore from, even if it is currently mounted. The "Restore From" dropdown only shows volumes, and no snapshots. What am I doing wrong?

To be honest I haven't really used DU for this type of restore for ages, but I see what you mean. In CCC if you hover over a snapshot, a "Restore" button shows up and it's easy. I just assumed it would be as easy in DU. Even activating a snapshot in DU doesn't help - the mounted snapshot doesnt show up as a restore valid source. I hope we're missing something. If CCC can do it, why can't DU?

I think I found it. See here:

APFS Snapshots: Restoring Your Mac to a Previous State

An overview of APFS snapshots, including what an APFS snapshot is, what it is used for, where it is stored on Mac, and APFS snapshots vs. Time Machine backups.

iboysoft.com

Seems like the option to restore from snapshot requires you to be in Recovery mode.

 

[Ben J.]

Yes, that seems like it would work well, assuming the System volume does not need to be restored (that is, there's been no macOS update to "undo").

The system volume part of the 'startup volume group' cannot be restored. It's a 'signed system volume'. you might be able to copy it, but it will never run if you try to restore it. The only way to create a bootable system volume is with macOS installers, Apple's online installation, or a bootable USB installer.

So when we're talking about restoring, we mean the " - Data" volume.

 

[Ben J.]

So you use CCC's "legacy bootable backup" feature for that? I was somewhat convinced (by Bombich's own documentation) that doing so was unnecessary and not recommended anymore.

Most folks will not see the need for a bootable backup, but one thing is that if something breaks on my prime drive, I can be back up and working on the bootable backup in a minute. Also rolling back a day or a week is done very fast because only modified files are copied.

I've used both CCC's 'legacy bla bla' to make it, and also by simply using a regular macOS installer to install it on a volume already containing a " - Data" volume - and the installer is clever enough to create the system volume group around the existing user files volume.

 

[Ben J.]

But how do I select the previous backup when using Setup or Migration Assistant? I tried with Migration Assistant and couldn't figure this out. It only showed the CCC backup as available as source but I couldn't select an older backup.

Like I said earlier, I don't think it can be done.
The logical answer is to first restore the snapshot to a new volume using CCC or DU in recovery mode, and then select that volume to import user accounts with Migration Assistant.

 

[Brian33]

Regarding the inability to use Disk Utility to restore a snapshot...

Seems like the option to restore from snapshot requires you to be in Recovery mode.

I booted from a bootable installer* (Monterey) and was still unable to use DU to restore a snapshot from the CCC backup volume. As far as I can tell, it's impossible to use Disk Utility to do this. A shame.

As we've already ruled out using Migration Assistant, it seems the only choices to restore an APFS snapshot are Time Machine and Carbon Copy Cloner.

( * I'm unable to test from Recovery mode. My iMac17,1 Late 2015 27" has a well-documented issue that prevents firmware updates unless a SATA device is installed internally. I believe that's the reason I cannot boot local Recovery, and Internet Recovery results in El Capitan, which cannot read APFS volumes at all.)