NFS Services Administrator's Guide

Configuring and Administering NFS
Configuring and Administering AutoFS
Chapter 2102
How AutoFS Sets Up Direct and Indirect Mounts
The automounts configured in a direct map may be mounted in various
places in the local file system; they do not have to be located under the
same parent directory.
The automounts configured in an indirect map are all mounted under the
same local parent directory.
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 force
AutoFS to reread its maps or
reboot your system before AutoFS
sees the changes you made.
Advantage: If you modify an indirect
map, AutoFS will see the changes
the next time it mounts the
directory, so you don’t have to force
AutoFS to reread its maps.
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.
Disadvantage: When automount
reads a direct map, it creates an
entry for each automounted
directory in the internal mount
table, /etc/mnttab. This can
cause the mount table to become
very large.
Advantage: When automount reads
an indirect map, it creates only one
entry for the entire map in the
internal mount table, /etc/mnttab.
Additional entries are created as
directories are actually mounted.
The mount table takes up no more
space than necessary, because only
mounted directories appear in it.
Table 2-6 Direct vs. Indirect Automounter Map Types (Continued)
Direct Map Indirect Map