SETUP:
  1. MacBook Pro running Catalina Public Beta formatted APFS (encrypted)
  2. External drive formatted APFS with two Volumes
    1. CLONE (encrypted) containing a clone of the MBP drive while it was still running Mojave beta
    2. ARCHIVE containing miscellaneous archived files
THE TASK:
  • Convert the Mojave beta to a release version of Mojave to provide a stable system for routine use during the early phases of Catalina beta testing when not everything is working as advertised.
THE PROCEDURE:
  • Boot from the Internet Recovery Drive (hold ⌥⌘R) during a cold boot, then select your network and enter the network password) This installs the latest release version of MacOS compatible with your computer.
  • Patience is a virtue and eventually MacOS 10.14.5 is installed over MacOS 10.14.6 beta on CLONE
  • The system boots from Mojave and then the unexpected happens…
    • I am prompted for the Macintosh SSD password (not unexpected)
    • I am prompted for the Macintosh SSD - Data password (what the H3𝄞𝄞 is Macintosh SSD - Data?)
    • It says Macintosh SSD so I assume it is the same password and enter that. — It works
THE RESULT:
  • Both Macintosh SSD and Macintosh SSD - Data appear in the Finder Sidebar
  • Disk Utility Shows both as APFS volumes on the same drive
  • Macintosh SSD appears to be the Recovery Volume
  • Macintosh SSD - Data appears to be the complete boot volume with all the invisible files and folders visible.
COMMENT:

This may be normal when dealing with AFPS Volumes, but exposing the recovery drive and hidden files and folders on the external volume seems risky and contrary to long held Apple Practice. By-the-way neither of these volumes can be dismounted in Finder but the may be because they are not external drives. I can report this but I would like to know if anyone else has seen this behavior so I can determine if it is a function of my procedure?

If we knew what it was we were doing, it wouldn't be called research, would it?

— Albert Einstein