 | | | Cluster Sendmail? | Cluster Sendmail? 2005-05-18 - By John Haxby
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Christopher McCrory wrote:
>On Wed, 2005-05-18 at 12:45 +0300, Jussi Silvennoinen wrote:
>
>
>>>IMHO, you don't need HA Cluster for building HA sendmail solution -
>>>using several MX records with the same priority is enough.
>>>
>>>
>>Only for certain problems. Outgoing mail gateway for MUA's don't benefit
>>from multiple MX's. HA/Loadbalancer solution is necessary.
>>
>>
>Multiple A records might work
>
>mail.outgoing IN A 172.31.31.1
> IN A 172.31.31.2
> IN A 172.31.31.3
> IN A 172.31.31.4
>
>
>
That's all fine and dandy provided none of the mail.outgoing machines
has the termerity to crash while there is mail in its mail queue.
Multiple A records do load balancing to a certain extent (DNS round
robin) but as Jussi has just pointed out, the abiliy of some MUAs to
deal with multiple IP addresses for one name is, shall we say, lacking
which makes them pretty well useless for availability.
MX records terrific for connectivity problems, and you should have them,
but I suspect that MUAs have even less support for MX records.
Anyway, neither are any good for HA unless you can guarantee that a
machine will only crash when its mail queue is empty :-)
jch
jch
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