When multiple layers are defined in the automounter files, the mount process becomes more complex. Suppose that you expand the /etc/auto_shared file from the previous example to contain the following:
# share directory map for automounter # ws / gumbo:/export/share/ws /usr gumbo:/export/share/ws/usr
The mount process is basically the same as the previous example when the /share/ws mount point is accessed. In addition, a trigger node to the next level (/usr) is created in the /share/ws file system so that the next level can be mounted if it is accessed. In this example, /export/share/ws/usr must exist on the NFS server in order for the trigger node to be created.
Do not use the -soft option when specifying hierarchical layers. Refer to Autofs Unmounting for an explanation of this limitation.