Using automount and File System Org under NFS

[Dwight D. McKay]

I've worked up a method for using automount here at ECN which gives us
access to all our user file systems from any Sun as well as manual page
service from the least loaded manual page server.

It works like this:

According to the automount source (the only "true" reference :-)), the
automounter reads the "auto.master" YP map to get it's options.  Ours
looks like this:

# ECN wide configuration map for automounter
/net auto.net -rw,hard

This has automount use /net to mount things from a list contained in the
YP map auto.net.  I created auto.net myself and added it to the YP
makefile, etc.

Part of our auto.net looks like this:

# DON'T TOUCH IT
# ECN-wide automounter configuration file.
# This file is kept in /usr/src/etc and is both RCS'd and rdist'd.
# first we list *the* source server
SRC             -soft,ro        orchestra:/usr/src
# next we list the manual page servers
MAN             -soft,ro \
        aquarium:/usr/man \
        author:/usr/man \
        bank:/usr/man \
        cidmac:/usr/man \
        eadsbridge:/usr/man \
        gus:/usr/man \
        iies:/usr/man \
        molecules:/usr/man \
        orchestra:/usr/man \
        rvl3:/usr/man \
        spectrum:/usr/man \
        stable:/usr/man \
        zoo:/usr/man
# next come the /home's on the network's file servers
ampere          -hard,intr,rw   ampere:/home/ampere
ampere2         -hard,intr,rw   ampere:/home/ampere2
aquarium        -hard,intr,rw   aquarium:/home/aquarium
aquarium2       -hard,intr,rw   aquarium:/home/aquarium2
atoms           -hard,intr,rw   atoms:/home/atoms
atoms2          -hard,intr,rw   atoms:/home/atoms2
author          -hard,intr,rw   author:/home/author
author2         -hard,intr,rw   author:/home/author2
bank            -hard,intr,rw   bank:/home/bank
bank2           -hard,intr,rw   bank:/home/bank2
cidmac          -hard,intr,rw   cidmac:/home/cidmac

There are more file servers, but that should give you the basic idea.
This shows three basic catagories of automount use.  Let me explain each
one:

Sources:

Our local source pool is on a single source machine.  On ALL our other
Suns there's a sym-link:

	/usr/src -> /net/SRC

Whenever a user needs to look at sources which are available for him to
look at he just does something like: "more /usr/src/ecn/foo.c"; automount
kicks in, and he gets what he needs.  This gives wide access to a single
filesystem without the penlty of being "hung" if the source server goes
down and you're not using the sources.

Manual Pages:

This entry in auto.net shows off a really nifty automount feature,
multiple sourcing.  What is says is: get /usr/man from the first of these
machines to respond.  It works by sending a packet to each of those
machines and picking the machine which gets an answer back first.  We use
a sym-link as above to trigger the whole thing:

	/usr/man -> /net/MAN

It works pretty well, giving users manual page service even if one or more
of the possible manual page servers is down.  Furthermore, heavily used
servers don't get futher bogged down with manual page service.

User Files:

This is pretty straight forward.  Our /home holds mostly sym-links to
/net.  Stuff like:

	/home/aquarium -> /net/aquarium
	/home/cidmac -> /net/cidmac

I wrote a short sed script which we run build the sym-links we need from
the auto.net YP map.  It gets run by cron and we use rdist to send out
auto.net.  The result is automatic filesystem availability when new file
servers get installed.

Automount is really nifty!  It deserves better documentation.  I hope my
example has helped in that regard.

--Dwight D. McKay
--Engineering Computer Network, Purdue University
--Work: mckay at harbor.ecn.purdue.edu, (317) 494-3561
--Home: ...rutgers!pur-ee!mckay!dwight