[CentOS] Load balancing email?
Nathaniel Hall
lists at nathanhall.net
Tue Oct 25 23:52:34 UTC 2005
Benjamin Smith wrote:
>Using multiple A records is good for performance balancing, but what if one of
>the systems fails?
>
>Using your cocnfiguration, the delivering mail server has an "a" record and a
>single MX, so it wouldn't try the other mail server in the case of a failure,
>right?
>
>Whereas, by listing multiple IPs and mx1/mx2, wouldn't the delivering mail
>server try the other address?
>
>Thanks,
>
>-Ben
>
>On Tuesday 25 October 2005 16:02, you wrote:
>
>
>>I once did this and it worked great:
>>
>> IN MX 10 mx.example.com.
>>
>>mx IN A 192.168.1.1
>> IN A 192.168.1.2
>>
>>...etc. Perfect DNS load balancing.
>>
>>Jack
>>
>>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
>>>--
>>>"The best way to predict the future is to invent it."
>>>- XEROX PARC slogan, circa 1978
>>>_______________________________________________
>>>CentOS mailing list
>>>CentOS at centos.org
>>>http://lists.centos.org/mailman/listinfo/centos
>>>
>>>
>>>
>>>
>
>
>
In addition to the entire Cyrus system, we have 3 MX records. All are
set to 0 with the exception of the lists server, which is set to 10.
--
Nathaniel Hall, GSEC
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