Enhanced AutoFS Administrator's Guide

Configuring and Administering AutoFS
Configuring Multiple Servers for an AutoFS Directory
Chapter 346
3. AutoFS needs the /etc/netmasks file to determine the local client’s
subnets in the replicated servers environment. You must manually
create and configure the /etc/netmasks file for the replicated
servers functionality to work properly.
The /etc/netmasks file contains Internet Protocol (IP) address
masks with IP network numbers. It supports both standard
subnetting as specified in RFC 950 and variable length subnetting as
specified in RFC 1519. When using the standard subnetting, there
should be a single line for each network with the network number
and the network mask to use on that network. You can specify the
network number and mask in the conventional IP ‘.’(dot) notation.
The network number is restricted to be a class A, B, or C network
number.
Consider the following example:
# network number netmask
128.32.0.0 255.255.255.0
The format is identical for variable length subnetting. However,
there should be a line for each subnet with the first field being the
subnet and the second field being the netmask.
The following example shows how AutoFS uses the /etc/netmasks
file to determine the local client’s subnets in the replicated servers
environment. In this example, the sage and thyme servers export
/nfs/mount. The IP address for the sage server is 15.43.232.30, and
the IP address for the thyme server is 15.244.10.20.
# /etc/auto_direct file
/nfs/mount sage,thyme:/user
#/etc/netmasks file on the client basil:
#network number netmask
15.43.234.210 255.255.248.0
AutoFS uses the /etc/netmasks file to determine the local client’s
subnets and mounts /nfs/mount from the sage server on the local
subnet.
To ensure that versions remain the same on all the servers, you need to
mount directories with multiple servers as read-only.