Apple once provided technical guidance on using an external drive as a home folder location in macOS. However, if such documentation still exists, it is now elusive.
Using an external, removable drive for a home folder requires meticulous attention to ensure it remains continuously powered. If it disconnects—particularly during a system update—macOS may fail to locate the designated mount point. In my case, this resulted in macOS replacing my home folder’s mount point (an external SSD) with a freshly initialised directory, complete with default user folders and documents.
TL:DR – One suspects that even the Genius Bar might take some considerable time to pinpoint such an obscure failure mode.
Missing mount point
For many macOS users, external drives or even network locations serve as essential home folder storage. The fact that macOS could arbitrarily overwrite the mount point without warning is deeply concerning.
A ghost from Unix past
Without knowledge of Unix system administration, a user might assume their data had vanished entirely. Diagnosing and resolving this issue consumed an entire morning. These sorts of issues were well known back in the days of NFS home folders for example on SunOS/Solaris.
Complicated to fix
The fix involved logging in under a separate admin account, deleting /Volumes/Home along with its subdirectories, detaching and reattaching the external drive, and then rebooting the system.
Upon restart, /Volumes/Home reappeared correctly, allowing a successful login. One suspects that even the Genius Bar might take considerable time to pinpoint such an obscure failure mode.
