A file tree can be expanded by connecting additional file systems to the root file system. This operation is referred to as “mounting”. Every directory in the file tree, with the exception of the root directory, can be selected as the mount point. Mounting takes place
automatically when POSIX starts if the file system is defined in the /etc/vfstab file or in “Administrate POSIX file systems” with the automount=yes attribute or
explicitly with the mount command. Only POSIX administrators can mount POSIX file systems.
When you mount file systems, please take the following into consideration:
While you are mounting file systems using the POSIX installation tool, no mount commands should be issued in the shell.
The original contents of the directories which are used as the mount point are “hidden” (files, subdirectories). Consequently the /usr directory should not be used as the mount point.
POSIX administrators can unmount mounted file systems again using the umount command.