[Dovecot] MySQL server has gone away

[Paul B. Henson]

On 1/12/2012 6:00 PM, Mark Moseley wrote:

> Jan 12 20:30:33 auth-worker: Error: mysql: Query failed, retrying:
> MySQL server has gone away

I've actually been meaning to send a similar message for the last couple 
of months :).

We run dovecot solely as a sasl authentication provider to postfix for 
smtp authentication. We're currently running 2.0.15 with a handful of 
patches from a few months ago when Timo fixed mysql failover.

We also see sporadic messages like that in the logs:

Jan 11 01:00:57 sparky dovecot: auth-worker: Error: mysql: Query failed, 
retrying: MySQL server has gone away

We do have a timeout on the mysql servers, so I don't necessarily mind 
this message, except we also see some number of these:

Jan 11 01:00:57 sparky dovecot: auth-worker: Error: 
sql(clgeurts,108.38.64.98): Password query failed: MySQL server has gone 
away

The mysql servers have never been down or unresponsive, if it retries, 
it should succeed. I'm not sure what's happening here, perhaps it tries 
the query on one mysql server connection (we have two configured) which 
has timed out, and then tries the other one, and if the other one has 
also timed out just fails?

I also see some auth timeouts:

Jan 11 22:06:02 sparky dovecot: auth: CRAM-MD5(?,200.37.175.14): Request 
10232.28 timeouted after 150 secs, state=2

I'm not sure if they're related to the mysql timeouts.

There are also some postfix auth errors:

Jan 11 23:55:41 sparky postfix/smtpd[20994]: warning: 
unknown[200.37.175.14]: SASL CRAM-MD5 authentication failed: Connection 
lost to authentication server

Which I think happen when dovecot takes too long to respond.


I haven't had time to dig into it or get any debugging info, but just 
thought I'd pipe up when I saw your similar question :).


-- 
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