NFS Services Administrator's Guide

Configuring and Administering NFS
Configuring and Administering the NFS Automounter
Chapter 2 67
How the Automounter Sets Up Direct and Indirect Mounts
When a user or program requests access to a remote directory, the
automounter mounts it under its own directory, called /tmp_mnt. Then,
the automounter creates a symbolic link from the mount point you
configured to the mount point under /tmp_mnt. For example, if you
configured the local mount point as /usr/bin, the automounter would
mount the directory under /tmp_mnt/usr/bin and create a symbolic link
from /usr/bin to /tmp_mnt/usr/bin.
The automounts configured in a direct map may be mounted in various
places in the local file system. Symbolic links are created from the
configured mount points to the corresponding mount points under
/tmp_mnt.
The automounts configured in an indirect map are all mounted under the
same local parent directory. A symbolic link is created from the parent
directory of the configured mount points to the corresponding parent
directory under /tmp_mnt.
Disadvantage: If you add or
remove mounts in a direct map,
or if you change the local mount
point for an existing mount in a
direct map, you have to restart
the automounter or reboot your
system before the automounter
sees the changes you made.
Advantage: If you modify an
indirect map, the automounter
will see the changes the next time
it mounts the directory, so you
don’t have to restart the
automounter.
Disadvantage: When a user or
program accesses a directory
containing many direct mount
points, all the directories are
mounted, whether they are
needed or not. This can cause a
flurry of mount activity.
Advantage: When a user or
program accesses a directory
containing many indirect mount
points, only directories that are
already mounted appear.
Table 2-4 Direct vs. Indirect Automounter Map Types
Direct Map Indirect Map