3. Automounter

Please note there are lots of discussions and documentation about automounters on the various linux resources.

Some of the text in this section has been plagerized from the NET-2-HOWTO maintained by Terry Dawson, terry@perf.no.itg.telecom.com.au

As a beginner, I found it difficult to find the information I needed to setup the amd and autofs automounters. I hope that the examples in this document will help you configure your network with the autofs automounter.

An automounter provides a convenient means of mounting filesystems on demand, i.e. when required by the system or the user. This will reduce the load on both the server and the client and provides a great deal of flexibility even for local server and it's filesystems.

An automounter provides 4 key features:

• An automounter makes exported filesystems on all servers listed in /etc/hosts available to your local host machine
• Wildcarding in the automounter makes it easy to mount remote directories to like-named mount points on the local host machine
• The automounting features of the programs mounts only the exported filesystems that is used from the possibly huge list of servers
• Having multiple servers improves the reliability of the servers and the network by removing the dependency on teh network

3.1 What Automounter Allows You To Do

• transparently mount your home dir if you need it
• transparently mount your backup directory as you need it
• transparently mount your mail server for reading and deleting
• compare files on the different servers
• allows you to have a common home directory server for all users to login and be authenticated and able to work from and workstation using any server in the network.
• increase the reliability of your LAN by removing the dependecies on a single server
• allows you to have acces to have access to large numbers of filesystems and directories, and only those that are used will be mounted, minimizing your risk from those unused servers.

-- is this a supported feature --

A rather useful mount called the union mount gives the automounter the ability to merge the contents of multiple directories into a single directory.

3.2 Some automounting tips excerpted from NET-2-HOWTO

Automounters use "maps" which define the filesystem to mount. different automounters maps are not compatabible with each other, eg: amd maps are not compatible with Sun maps, which in turn are not compatible with HP maps ad infinitum.

Sun automount maps can be converted to amd style maps by using the perl script in the contrib directory

automount2amd.pl

ypcat -k auto.nfs | automount2amd.pl >/etc/auto.Linux

-- check /etc/nsswitch.conf  also -- note for me...

You must have the portmapper running before starting the automounter

UFS mounts, in the case of Linux only, do not timeout. UFS mounts have been extended to deal with all varieties of linux filesystems (i.e. minix, ext, ext2, xiafs ...) with the default being minix. <<--- ???

Do not mount the filesystem over existing local directories unless you use a direct automount option, otherwise you will NOT be able to access the contents of your local directory. Typical examples are /home, /var/spool/mail, /usr/local, etc

Always turn on full logging with the `-x all' option to amd if you have any troubles

/usr/sbin/amd -x all -l syslog -a /amd -- /net /etc/amd.net

"amq -ms"  reports, as it will indicate problems as they occur

You do not configure the automounter from the /etc/fstab file, which you will already be using to contain information about your filesystems, instead it is command line driven.