Configuring AutoFS in Solaris 10

Introduction

Automounting enables a system to automatically mount and unmount NFS resources wheneve they are accessed. The resource remains mounted as long as the directory is in use and if not accessed for a certain period of time the directory gets automatically unmounted.

Automounting provides the following features:

Saves boot time by not mounting resources when the system boots.
Silently mounts and unmounts resources without the need of superuser prviliege.
Reduces netwrok traffic because NFS resources are mounted only when in use.

The client side service uses the automount command, the autofs file system and automountd daemon to automatically mount file systems on demand.


Working:

The automount service svc:/system/filesystem/autofs:default reads the master map file auto_master to create the initial set of mounts at system startup. These mounts are points under which the file systems are mounted when access requests are received. After the initial mounts are made the automount command is used to update the autofs mounts as necssery.

The automount service uses the following maps to perform automounting of file systems in demand:

Master Maps:
The master map auto_master determines the location of all autofs mount points. Given below is a sample auto_master file.

root@sandbox:/# cat /etc/auto_master
#
# Copyright 2003 Sun Microsystems, Inc.  All rights reserved.
# Use is subject to license terms.
#
# ident "@(#)auto_master        1.8     03/04/28 SMI"
#
# Master map for automounter
#
+auto_master
/net            -hosts          -nosuid,nobrowse
/home           auto_home       -nobrowse

Direct Map:
A direct map is an automount point. In this there is a direct association between a mount point on the client and a directory on the server. Direct map entries are preceeded by /- in the auto_master file.


Indirect Map:
An indirect map uses a substitution value of a key to establish the association of a mount point on the client and a directory on the server. The auto_home is an example of an indirect map.


Demonstration:

For this demo I'll perform an automount operation for a ZFS dataset to a client.

On the server:

Create the zpool and the corresponding dataset to be shared.

root@sandbox:/# zpool create spool c2t0d0
root@sandbox:/# zfs create spool/sfs

Check value of sharenfs property

root@sandbox:/# zfs get sharenfs spool/sfs
NAME       PROPERTY  VALUE     SOURCE
spool/sfs  sharenfs  off       default

Turn on the sharenfs property and verify that it's on.

root@sandbox:/# zfs set sharenfs=on spool/sfs

root@sandbox:/# zfs get sharenfs spool/sfs

NAME       PROPERTY  VALUE     SOURCE

spool/sfs  sharenfs  on        local

Add entry in /etc/dfs/dfstab file.

root@sandbox:/# grep sfs /etc/dfs/dfstab
share  -F nfs  -o rw -d "test share" /spool/sfs
root@sandbox:/#

Use the share command to activate the nfs shares.

root@sandbox:/# share

-               /spool/sfs   rw   ""

Verify that the share is active.

root@sandbox:/# showmount -e sandbox

export list for sandbox:

/spool/sfs (everyone)

On the client:

Check that the automount service is running.

root@trick:/# ps -ef | grep -w automountd

    root   528   527   0 13:48:16 ?           0:00 /usr/lib/autofs/automountd

    root   527     1   0 13:48:16 ?           0:00 /usr/lib/autofs/automountd

root@trick:/# svcs -a | grep -w autofs

online         14:04:34 svc:/system/filesystem/autofs:default

Create directory to use as automount mount pont.

root@trick:/# mkdir /auto

I'll be using a direct map named auto_test for the purpose of this demonstration. Now I'll add it's entry in /etc/auot_master file.

root@trick:/# grep test /etc/auto_master

/-      auto_test       -nosuid

Create the auto_test direct map file in /etc

root@trick:/# cat /etc/auto_test

/auto   -rw,nosuid      sandbox:/spool/sfs

Run automount -v to refresh the maps.

root@trick:/# automount -v

automount: /auto mounted

automount: no unmounts

Check if /auto gets automatically mounted when accessed.

root@trick:/# date

Tue Jun 27 15:14:51 IST 2017

root@trick:/# df -h /auto/

Filesystem             size   used  avail capacity  Mounted on

auto_test                0K     0K     0K     0%    /auto

root@trick:/# cd /auto/

root@trick:/auto# df -h .

Filesystem             size   used  avail capacity  Mounted on

sandbox:/spool/sfs     976M    21K   976M     1%    /auto

root@trick:/auto# date

Tue Jun 27 15:15:09 IST 2017

root@trick:/auto# df -h /auto/

Filesystem             size   used  avail capacity  Mounted on

sandbox:/spool/sfs     976M    21K   976M     1%    /auto