deoren: > Hi all, > > We've been using Postfix for years with good results, but in recent > years have moved to a load-balanced HAProxy front-end with multiple > backend relay nodes. I've consulted various sources during that time to > perform the initial setup and light tuning since then. > > The health checks are run often and simulate a full email delivery > session in an attempt to exercise the full configuration (including > alias resolution and other related db queries). > > This setup works pretty well, but occasionally there is enough of a > delay between one of the steps in the simulated delivery that the health > check fails and the node is marked as down. > > When this occurs I have been unable to determine exactly why the issue > occurs. I've adjusted various timeout and timing settings within HAProxy > and Postfix, so I assume that our mostly stock MariaDB 10.0.x > installation is likely to blame.
Have you looked in Postfix LOGs? For example, if there is a delay from the start of the probe to the first Postfix logfile record, then that would indicate a delay with looking up the client hostname, and then the address for that hostname. If there is a hiccup with MySQL, then you might see a Postfix warning around that time. etc. etc. Wietse > Do you have any recommendations for guides that cover tuning Postfix and > MySQL? I'd like to start there and work through the steps before turning > back to the configuration as a whole. > > Another option I'm considering is replicating the database contents > (where applicable) in MySQL to local SQLite databases that are synced to > the relay nodes, cutting MySQL/MariaDB out of the picture entirely. > > Our client node count is currently less than 100. > > Thanks in advance for any guides that you can reference! >