1. For Discussion: web virtual hosting vs mail virtual hosting
Hello,
I am the SysAdmin for a small webhosting/colocation compny, and we are in
the midst of re-designing our network, particularly our mail servers.
While in one of our discussions regarding failover load-balancing, and
interesting question was brought up:
Is it possible to have the mail boxes in different locations on the
server, and direct the user to their mailbox based on the domain?
Let me explain what I mean, using our web servers as an example (yes, I
know that HTTP and mail are different protocols, but please bear with
me)...
We have two Linux web servers, let's say IP addresses of '192.168.1.1' and
'192.168.1.2'. Each server is setup to listen on each IP address.
Each domain we setup is setup on one of the servers as it's "primary"
server, where the files are stored served from the local hard drive.
The site is then setup on the other server, which would server the site
off an NFS mount from an NFS server (the NFS server uses 'rsync' at
midnight each night to grab the updates/changes from the web servers
themselves).
The VirtualHost entries would look like this:
Primary:
<VirtualHost 192.168.1.1:80>
DocumentRoot /websites/[0-9,a-z]/customerdomain.com
...
</VirtualHost>
Secondary:
<VirtualHost 192.168.1.1:80>
DocumentRoot /nfs/websites/[0-9,a-z]/customerdomain.com
...
</VirtualHost>
Our router is then setup with "priority load balancing": it knows that if
the host header contains 192.168.1.1, to go to Server A (which serves up
the site locally), but if he is down, go to Server B (which serves the
site off the NFS mount). Of course, the advantage to this setup is that
we could lose either server, and still be fine (some people just would not
be able to FTP their site chanes), *or* we could lose the NFS server, and
still be okay. Of course, if we lost a server *and* the NFS server, then
we piss off half of our customers :-)
So, now for the questions:
1. Is something similar possible for mail servers (it's not so much the
contents of the email directories I would care about as much as the
existence of the mailboxes themselves)
2. If not possible (and I am almost sure it is not), what is the reason?
I would guess it is the different way the protocols work. Is there
material you could point me towards to learn about htis (the RFC's??)
TIA for your patience regarding this slightly off-topic post... :-)
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