mail

[David Wiseman]

We have been successfully using a common mail spool directory for the past
two years. We have only seen a very few messages disappear.

In our situation we run our network of 3 servers and some 40 clients
(mostly diskless but with some dataless) so that every workstation sees an
identical filesystem. This means that any user can log onto any
workstation and see his files, along with everything else. We are
currently running SunOS 4.0 (ugh).

Each of the client /var/spool/mail directories (and /usr/spool/mail under
3.x) is a symbolic link to the mail spool directory on the server that is
acting as mailhost. Needless to say, the mail spool directory on the
server is also a symbolic link; we do not mount server:/var but rather put
the mail spool directory somewhere else. We mounted /usr/spool/mail under
SunOS 3.x but decided that wasn't necessary under 4.0.

We ensure that our clients (and all servers but the mail host) do no local
delivery at all: they punt everything to the mail host. We also hide all
client names from the outside (and inside) world inside of the sendmail.cf
on the server. The result: to mail our network appears to be one machine.

As I mentioned at the start, we have had no problems that are truly
traceable to the locking problem mentioned previously. Only two or three
users have complained that mail simply disappears; usually it can be
traced to something else. Since the amount of mail I receive in any one
day is approaching transfinite, and I can only recall one instance where
mail disappeared when I knew it was there, I do not have any reason to
believe that what we are doing is unsafe.

magi    David Wiseman, Network Manager
        Department of Computer Science
        The University of Western Ontario
        London Ontario Canada N6A 5B7