Data-only backup with 3.6.2

[mschmitt]

I've just upgraded my main Mac to Catalina (was stuck on Mojave due to 32-bit apps). I do have full clones, one on a SSD drive.

But I have two other 1.5 TB HDD drives, which I rotate offsite.

For these drives, making a bootable backup doesn't seem to be a good idea; for one thing it would be problematic to boot from them to enable encryption. Another is that they're tight on space if I try for a bootable backup.

Ideally I'd just backup the Data volume. I see in the blog mention of a data-only backup in 3.5 and later. And it says that a data-only backup to a pre-encrypted volume is supported. But how?

As an experiment, I selected the standard "Backup - user files" script, but it still gives the warning that "Encrypted volume is incompatible", suggesting that I erase and copy.

So I'm not sure what my options are.

I saw mention in another post that you may be able to use 3.2.5, but then how would you have two versions of SuperDuper installed at the same time? They'd compete for settings.

Is there a way to use 3.6.2 to backup the Data volume to an encrypted drive? If not, what is the procedure for backing up the Users folder (plus maybe a few other non-system folders) to a pre-encrypted drive? If not, will Catalina let me encrypt a non-bootable drive?

[dnanian]

You can't make a Data-only backup on Catalina. Only Big Sur and later.

[mschmitt]

I tried using a script that excludes System, but from what I can tell, it has copied the entire system volume without loading or respecting any of the script commands.

That is, it didn't load the script commands until it got to the Data volume, and by that time it is too late.

[dnanian]

Yes, under Catalina it always copies the system volume. The script does not apply to the system volume copy.

[mschmitt]

So it would copy the system volume even if using the "Backup - user files" script? And basically under Catalina there's no way to avoid creating a bootable backup?

Note: I tried something else: I mounted just the data volume of my SSD backup only, thinking then it could just copy it without considering it to be part of a macOS volume. But while it definitely is mounted (I can open it from the Terminal), the Copy source picker won't show it as an option.

[dnanian]

Yup. Since the behavior had already been defined with regard to Smart Update (which can update the OS under Catalina) it always copies the OS. The data volume on its own (if given the Data role) won't show up.

[mschmitt]

I succeeded in backing up Catalina to the 1.5 TB drive, with ~400 GB to spare, and it is fully encrypted.

As others have noted, it is no fun booting from a HDD. Especially annoying is that you can't open the Security & Privacy preference pane to turn encryption on; it times out and gives an error.

I think the problem is that XProtect is busy scanning the entire drive, which takes hours on an HDD (and that's even though presumably after the initial SuperDuper clone, the HDD is perfectly defragged!).

I finally got the Security & Privacy pane to load by using the renice command to bump up its priority:

1. Open System Preferences
2. Open Terminal (which in itself can be a struggle)
3. ps ax | grep Preferences to get the PID of System Preferences
4. sudo renice -n -10 "pid" where pid is the PID found in step 3
5. Select Security & Privacy