Rolf E. Sonneveld:
> On 12/14/11 1:00 PM, Wietse Venema wrote:
> > Rolf E. Sonneveld:
> >> Hi, all,
> >>
> >> sorry if this has been asked before, I browsed the archives and could
> >> not find this mentioned. Running Postfix 2.8.6. I'm planning to use the
> >> Dovecot SASL implementation. Is there a way to define multiple Dovecot
> >> servers to achieve redundancy and to prevent problems in case one
> >> Dovecot server / process is down?
> > At this time, multiple servers would require inet:host:port where
> > "host" resolves to multiple IP addresses.
>
> Do you mean by this that, in a round robin setup like:
>
> auth.example.com IN A auth1.example.com
> auth.example.com IN A auth2.example.com
auth.example.com IN A 1.2.3.4
auth.example.com IN A 1.2.3.5
> and:
>
> /etc/postfix/main.cf:
> smtpd_sasl_path = inet:auth.example.com:port
>
> Postfix would try automatically auth2.example.com when it discovers
> auth1.example is down (in case it gets
> auth1.example.com,auth2.example.com (in this order) from the DNS resolver)?
The Postfix routine that makes a TCP connection will try each IP
address (that the getaddrinfo() system routine returns for the
hostname) and will stop when the connection succeeds, or when there
are no more IP addresses.
I'm betting that your getaddrinfo() will return multiple addresses
with lookups from DNS. It appears that Linux handles that.
Wietse
> > /etc/postfix/main.cf:
> > smtpd_sasl_path = inet:host:port
> >
> > I recall that Linux won't allow you to do that with /etc/hosts,
> > so you'll have to use DNS or *BSD.
>
> Thanks,
>
> /rolf
>
