Ian Eiloart escribió: >
>
> --On 9 November 2007 13:27:48 +0100 Adrian Chapela
> <achapela.rexistros@???> wrote:
>
>> Ian Eiloart escribió:
>>>
>>>
>>> --On 9 November 2007 12:50:43 +0100 Adrian Chapela
>>> <achapela.rexistros@???> wrote:
>>
>>> Provision of IP failover is highly dependent on the platform that
>>> you're using. It's not required for MX availability, because remote
>>> servers will try all your advertised servers. It is required for MSA
>>> availability, because MUAs will not.
>> Yes you are right, but if you have clients locally on your company, they
>> must connect to a smtp server and DNS round robin it isn't the best
>> solution to get hight availability (IMHO).
>
> That depends what you mean by "client". If you mean an MTA attempting
> to relay, then round robin should do reasonably well at low cost. If
> you mean mail user agents (MUAs) then round robin doesn't help at all,
> as I said. I am talking about MUAs >
> Absolutely right - DNS round robin does nothing for MUAs (mail
> clients). Mail clients won't attempt to connect to a second IP
> address, so DNS round robin does nothing to achieve high availability
> at all. It merely serves to provide load balancing. Actually, if that
> makes the servers more capable, then you may get some small
> availability gains.
>
> So, for high availability you need to ensure that every IP address in
> the round robin is highly available. For that, you need IP failover.
> For MX hosts, you don't need IP failover because remote servers should
> try all the available IP addresses. Yes... >
>>>
>>> We use MacOSX servers. OSX has a reasonably easy to configure IP
>>> failover mechanism, as long as you only have two servers. When we went
>>> beyond two servers, we deployed spread and wackamole which make
>>> failover configurations for any number of servers trivial. For
>>> example, we have 12 imap server IP addresses, to ensure good load
>>> balancing with either 4, 3 or 2 available hosts. Wackamole simply
>>> needs to know what the addresses are, and endeavours to share them out
>>> equally among available servers.
>> Yes.. it sounds perfect...
>>>
>>> <http://www.spread.org/>
>>> <http://www.backhand.org/wackamole/>
>>
>> Best regards.
>
>
>
