raattgift wrote:"There is nowhere written in the docs"
Please see both paragraphs in the "User Home Directories" section in http://images.apple.com/business/docs/Autofs.pdf
and the mnthome(1) man page.
Man, I really don't know, why you are doing this to yourself. The docs from 2009 are generation obsolete. The paragraph literally means the consequence that you can't log another user to a machine while network account is logged on (even with fast user switching) - as I said before (ok, this can be easily solved by auto home mounting of NFS, but Apple pretend, there is no NFS).
You already forgot that: we are on open directory, where you have path to user dir (used for local logins) and user dir url (for remote logins). During local login the path is used (and specially with autofs and autohome mounts local to the machine are converted to links + mac doesn't allow local mounts, right?). So we have just local filesystem with user dirs - like standalone mac without directory bond. So specially for you this time, macos is trying to unmount this filesystem upon logout - I don't care, I can watch for folder change via launchd and remount. And now surprise surprise - if this fs is a let's say zfs root fs on a zfs pool, this umount is successful even if there are other mounted filesystems on it with open files - those stay mounted in the air and any try to remount the root fails. And let me again tell you, that I'm not talking about user home dirs as a mounts. One partition, one filesystem holding user dirs + public shares (default mac factory setup).
I'm talking about ZEVO allowing to umount zfs filesystem with open references on it / active mounts within a hierarchy. and that is a fail.
And the Apple's concept of "Full path" as path to directory under which user home is, than "Path to Home Folder" which is one level under pointing to actual user dir + Share point URL splitted into mount URL and path is again fail and shooting into own positions, because what happens if the mount is local to the machine? Remember, auto mount takes the "Path to Home Folder", creates a symlink to actual directory, ... which is by mistake/bug during logout resolved into filesystem mount - if and only if this is another filesystem suposed holding the user dirs directly under it's root dir.