How do I clone the local drives' Users directory ACL to an external drive? My local drive (Macintosh HD) runs out of space so I want to setup an external drive (External HD) with the same /Users directory and associated ACL as on the Macintosh HD drive and offload some of the more data-heavy directories there (Photos, Music, Movies).

Get Info on the User directory of Macintosh HD shows these permissions:


I've tried to use the [+] button (after authorising with admin privileges), but it didn't seem to allow me to add 'special' users. How do set 'system' to have R&amp;W access, for instance?

Before making such a fundamental change, I wanted to see if I should use sudo chown -R system:system system to this directory. Though this would only change the owner and not necessarily let other users also have access to it. AFAIK, users 'system' and 'admin' are in different groups too.

Also, if I do a Get Info on a user I see this "Fetching..." line, which never seems to go away. What is this meant to fetch? A list of users who have access to this directory?
Ok, so turns out that all I needed to do was sudo chown root:admin /Volumes/External_HD/Users

Obviously, the checkbox next to "Ignore ownership on this volume" should be un-ticked. You can only see this on Get Info of the Volume: