[Dovecot] mysql auth failover failing

[Paul B. Henson]

On 9/12/2011 5:30 AM, Timo Sirainen wrote:

> This works okay enough with PostgreSQL because it does asynchronous
> lookups, so two simultaneous lookups create a second connection.
> MySQL does synchronous lookups though, so the second connection is
> normally never created.

If I could, I think I'd rather run postgres; but so many things only
support mysql you can't really get away with running only postgres, and
it's not worth the effort to run two separate sql services <sigh>.

> I suppose the fix to this would be to always connect to all SQL
> servers at startup.

Perhaps it could be an option, either load balancing between all
available servers, or only using later listed servers when the earlier
listed ones are failing. For my purposes, either way is fine, as long as
authentications don't fail :). The other contributor to this thread, who
has a local mysql replica listed first and the central master listed
second probably wouldn't want the load balanced between them.

> It should have created the second connection here and not fail..

Based on the network traffic, it is really pounding the primary trying
to connect, and occasionally connecting to the secondary only to
immediately disconnect after either only one or very few queries.

> I'll try to debug this soon.

Thanks; let me know if there's anything I could do to help, or if there
are any potential fixes you would like tested.


-- 
Paul B. Henson  |  (909) 979-6361  |  http://www.csupomona.edu/~henson/
Operating Systems and Network Analyst  |  henson at csupomona.edu
California State Polytechnic University  |  Pomona CA 91768