NFS Services Administrator's Guide (B1031-90072, March 2011)

Notes on the -hosts Map
The -hosts map is a built-in AutoFS map. It enables AutoFS to mount exported directories from
any NFS server found in the hosts database, whenever a user or a process requests access to one
of the exported directories from that server.
CAUTION: You may inadvertently cause an NFS mount over X.25 or SLIP, which is unsupported,
or through a slow router or gateway, because the -hosts map allows NFS access to any reachable
remote system. Mounts over slow links can cause excessive retransmissions and degrade the
performance for all users.
When a user or a process requests a directory from an NFS server, AutoFS creates a subdirectory
named after the NFS server, under the local mount-point you configured in the AutoFS master map.
(The conventional mount-point for the -hosts map is /net). AutoFS then mounts the exported
directories from that server. These exported directories are now accessible.
The -hosts map is an indirect map. It uses the hosts database (the /etc/hosts file, the NIS
hosts map, LDAP, or BIND [DNS]) to discover the host on the network. The NSS configuration
determines which name services to search for host information. For more information on configuring
the NSS, see nsswitch.conf(4).
For example, if the server, Basil exports /opt and /apps, and a user on your NFS client enters
the following command:
cd /net/basil/opt/frame
the subdirectory, /basil is created under /net, and /opt is mounted under /basil.
Figure 13 shows the automounted file structure after the user enters the command.
Figure 13 Automounted Directories from the -hosts Map—One Server
In the following example, the server thyme exports the directory /exports/proj1, and a user
enters the following command:
more /net/thyme/exports/proj1/readme
The subdirectory /thyme is created under /net, and /exports/proj1 is mounted under
/thyme.
Figure 14 shows the automounted directory structure after the user enters the second command.
Figure 14 Automounted Directories from the -hosts Map—Two Servers
68 Configuring and Administering AutoFS