What's the best way to convert a backup volume to APFS in Mojave? I didn't see any evidence that SuperDuper! was going to do it for me.
Situation is:
- Internal SSD was previously converted to APFS by High Sierra.
- I've been SuperDuper!ing to a volume on a backup drive that was still HFS+.
- I upgraded internal SSD to Mojave.
- Since HFS boot volumes are unsupported in Mojave, I wanted to convert the backup to APFS. (Yes, I know that you can boot Mojave from HFS but it isn't a supported configuration, and you wouldn't be able to update it.)
Disk Utiliity had Convert to APFS greyed out for some reason. I considered using the command line, but a goal was to create the APFS container with the proper Recovery volume, and I didn't know if that would happen automatically.
What I ended up doing is running the Mojave installer while booted internal, to upgrade the external volume even though I'm just going to overwrite the results with SuperDuper! anyway. That worked (except for a boot-to-black-screen issue), but the computer is not usable while it is running the install. Also, there is some evidence that at the end it actually started up on the newly upgraded backup volume, which
I did not want since there was danger of it synching out-of-date files.