[CentOS] Load balancing email?
Craig White
craigwhite at azapple.com
Tue Oct 25 22:56:57 UTC 2005
On Tue, 2005-10-25 at 17:17 -0500, Nathaniel Hall wrote:
> Benjamin Smith wrote:
>
> >Currently, we have two mail relays for inbound messages, and a third for POP.
> >
> >The inbound messages go thru all the CPU-intensive anti-spam stuff, and then
> >they relay it to the POP server for pickup.
> >
> >Currently, one of these is the "primary", and the other is "secondary", and
> >I'd like them to be considered more or less as equals, since the "primary"
> >system is getting beaten pretty hard.
> >
> >The DNS zone file says something like this:
> >
> >###############################
> >@isp.com
> ><SNIP>
> > IN MX 100 mx1.isp.com.
> > IN MX 1100 mx2.isp.com.
> ><SNIP
> >################################
> >
> >I seem to recall that I make them act as "equals" by simply changing this to
> >
> >###############################
> >@isp.com
> ><SNIP>
> > IN MX 100 mx1.isp.com.
> > IN MX 100 mx2.isp.com.
> ><SNIP
> >################################
> >
> >so that they both get about the same amount of inbound messages. Has anybody
> >here actually done this? How well does this work as far as failover if either
> >system fails?
> >
> >-Ben
> >
> >
> I actually recommend using a Cyrus system. We are able to handle about
> 20,000 accounts with the following servers:
>
> 3 front ends (Horde, IMAP, Spam Assassin, SMTP, etc load-balanced at the
> firewall)
> 2 storage servers (actually stores the e-mails)
> 1 MySQL server (Used for Horde)
> 1 list server (for MailMan)
>
> This can easily be added to. We use it a lot so that we can remove a
> system from the load balance and upgrade one server at a time. We can
> eventually take all but one out and have them upgraded and then swap the
> last one with all of the new servers. It appears to be seamless to the
> users and sure helps with being able to do maintenance at any time of
> day and you don't have to have overly powerful servers to get it working
> well.
----
Let me see if I get this straight - OP asks about multiple MTA & dns/MX
records and your answer is about MUA's and delivery agents. Good thing
at least we all speak English.
OP - your logic is good - should work. I hesitated to answer since I
have no first hand experience with multiple MX records of same value for
priority.
Craig
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