On Wed, Mar 02, 2011 at 10:58:43PM +0000, myrdhin bzh wrote:
> >> # in master.cf :
>
> >> slow unix - - n - 5 smtp
>
> > Something like that. The "5" process limit will mean that with multiple
> > "slow" domains at most 5 delivery processes will be used in total for
> > all "slow" destinations. This may not be what you want. It can however
> > reduce instances of a single MX host getting many connections when it
> > serves multiple slow domains. The downside is a potential bottleneck.
>
> My /etc/postfix/transport file contains one domain (domain.tld). This domain
> have 10 SMTP servers (smtp.domain.tld with round-robin DNS configuration). I
> know that each SMTP server can only accept 3 concurrency connections.
>
> I find lot of lines like this in my mail.log :
>
> Mar 2 20:31:04 localhost postfix/smtp[5394]: 2A5529C4429: host
> smtp.domain.tld[xxx.xxx.xxx.xxx] refused to talk to me: 421 mwinf5c20 ME Trop
> de
> connexions, veuillez verifier votre configuration. Too many connections, slow
> down. OFR004_104 [104]
>
> How can i configure my postfix ?
Instead of setting a very low concurrency limit (the default is 20
which should be fine for 10 MX hosts that tolerate 3 connections each),
disable demand connection caching for this domain. And also:
master.cf:
slow unix - - n - - smtp
-o smtp_connection_cache_on_demand=no
main.cf:
slow_initial_destination_concurrency = 3
slow_destination_concurrency_failed_cohort_limit = 3
slow_destination_concurrency_positive_feedback = 1/5
slow_destination_concurrency_negative_feedback = 1/8
This will spread the load more evenly among the 10 (you say equal-weight)
MX hosts and will reduce the rate at which concurrency is increased
while improving error tolerance so that the destination is not throttled
prematurely.
--
Viktor.
