On 12/12/11 16:14, Simon Hobson wrote:
[email protected] wrote:We are looking at setting up a cluster of outbound mail servers using policyd, and I was wondering what the configuration of the mysql database would look like. Is the database supposed to be independent for each node that is serving mail, or is it possible to have all of the mail servers pointed to the same database, sharing the cumulative logging for policies? The only policy we plan on implementing is a limit on how many messages a SASL user can send per hour.You have a number of options. You don't really want a separate database per node as you'll just end up with out of sync data and a general nightmare.So your options are (AFAIK) : 1) Run one policy server (and backing database) and call if from each mail server. This is what I've done for a small cluster - and the shared DB is also used with Postfix Admin. This is what I'd suggest as the load is actually fairly low, even for a busy server. 2) Run a shared backend database, but a separate policy server on each mail server. 3) Run a separate policy server on each mail machine, AND a separate database (replicated) for each server. TBH, I can't see any point in 3 - just a complication too far. Option 2 may have some merit, but probably limited performance advantage. Of course, if you want resilience then you could run a replicated pair of backend databases, with a policy server each, and split your mail servers between the policy servers. Or various other permutations. FWIW, when I was having some performance issues (eventually tracked down to a bug in the version of<something> I was running, I found that my limiting factor was Postfix - it seems to be limited to about 2 queries/s to the policy server from each thread. I did some tests and found I could easily load up the single policy server with multiple streams of queries and it would chew through them at something like (IIRC) 60/s even on my fairly low spec machine running multiple guests under Xen.
Totally excellent reply here from Simon. -N
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