Catalina is a different drive format (APFS), and when Catalina is installed it makes two partitions.....I only discovered this when I installed it on my husband's PowerBook Pro --- thankfully it all worked ok and we've not had any hitches, but then he's not running a lot of stuff. one is sort of sandboxing the Macs system and the other partition is your own stuff.
It seems like Apple are headed down the path of locking things down more and more though their excuse I read was to make the system even tougher against virus and hackers. Fair enough.
I was about to explore Virtual Box and whether that would be feasible to run another system inside that. Yet to discover that.
One thing I did read is that if you install Catalina and it goes whoopsie then you have the chance to do a restart/command/R and that the Mac makes a "screenshot" recovery before install. ?But not had to test that ?one.
Jude
