On 6/1/05, Ashley M. Kirchner <ashley(a)pcraft.com> wrote:
First, the question: How to build redundancy on a "users" server?
What's behind it: When our main users server goes down, no one can
log in to check their e-mail. So the problem as it was presented this
morning was to research some way to make it so that if that server goes
down, users still have a way of getting to their e-mail or login to
their accounts for that matter. Now, the setup we have is a bit
different from most people I'm sure. Incoming e-mail flows as follows:
Internet -> MX server -> spool server (NIS+ slave)
Our "users" server - also our NIS+ master - (which is a totally
different machine) does an NFS mount of the spool server on /var/mail/
and voila, e-mail. When our users use imap/pop to check/get/send
e-mail, they log in to that "users" server to do so. No one
communicates directly with the spool server. So when the "users" server
goes down, no one can get to their e-mail. The question: what kind of
redundancy can I build so that if that server were to go down, that
users can still log in (to -something-) and still access everything they
need. Presumably this would be a separate machine and that the fall
back would be transparent to them. I just don't know how or what.
besides the obvious (keeping the server running) id consider you think
about a mirroring type of system, i am not sure if anyone has yet
tried something like that for mailservers, at least for webservers its
pretty common to have 2 or 3 or more servers, who are updating their
content with each other at special given times.
first things that come into my mind when thinking on bringing that
system to a mailserver:
1. write your own mailserver (pop, imap, smtp, whatever...) and insert
a "duplicate mail to host xxx.xxx.xxx.xxx folder something..."
technic, or just change an existing opensource server to do that for
you.
2. have a non-real-time backup solution (cronjobs, caching,
whatever...) do the job on keeping them updated...
for the switch in im somehow thinking on dns, mx entry, isnt there
something like a backup mx entry?
well, so much bout my thoughts, maybe someone else has better ideas,
anyhow, i hope i wasnt too far away from it.
--
H | I haven't lost my mind; it's backed up on tape somewhere.
+--------------------------------------------------------------------
Ashley M. Kirchner <mailto:ashley@pcraft.com> . 303.442.6410 x130
IT Director / SysAdmin / WebSmith . 800.441.3873 x130
Photo Craft Imaging . 3550 Arapahoe Ave. #6
http://www.pcraft.com ..... . . . Boulder, CO 80303, U.S.A.
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