I've been trying off and on for over a year to relocate a single database from my root volume to a larger, RAIDed, external volume, with no success.
My first problem was that the manual contained two conflicting sets of instructions, neither one of which worked. That took three months to resolve, requiring the team to write up a third procedure. It also didn't work.
Recently I bit the bullet and sat down to produce a detailed log of the failure I receive when I follow the current instructions. I submitted it as a bug:
https://bugs.mysql.com/bug.php?id=102476
Within six hours, it was declared "not a bug," accompanied by a rude answer of the form, "You did it wrong (I won't tell you how)."
I'm hoping someone here has either achieved this on MacOS, or can explain what I did wrong in the log and how. All the details are at the URL above. Thanks.