LDAP: Connection appears to be hanging, reconnecting

[Matthias Egger]

Hello Simon

On 12/16/2014 05:38 PM, Simon Fraser wrote:
> This is speculation, but what has happened to us in the past is that the
> LDAP server stopped responding to queries, but the TCP socket was still
> open for connections. A new TCP connection would be established, but the
> daemon would not be notified of it.
> 
> So, depending on precisely how the first LDAP server crashed, it may not
> be the same test as killing the process, but closer to sending it 'kill
> -STOP' (and then 'kill -CONT' afterwards, obviously)

Thank you very much for that hint. You were right. When i -SIGSTOP the
slapd i receive a similar behaviour of dovecot as we had a few weeks ago.

So do you (or someone other) has a hint on how i could work around such
a situation?

I found a statement from Timo Sirainen from June 2011:

http://www.dovecot.org/pipermail/dovecot/2011-June/059905.html

"...Fallbacking to another LDAP server is done by OpenLDAP internally..."

So i thought, there should be a possibility to "tweak" the ldap.conf.

I then found a german Post:

https://listen.jpberlin.de/pipermail/dovecot/2014-June/000506.html

Where someone mentioned some ldap.conf Settings:

BIND_POLICY 	soft
TIMELIMIT       5
NETWORK_TIMEOUT 5
TIMEOUT         8

and a link to:

http://www.linuxquestions.org/questions/linux-enterprise-47/ldap-failover-timeout-client-setting-847718/

which also uses these two settings:

BIND_TIMELIMIT 10
IDE_TIMELIMIT 10

I gave i try to them, but the result was still the same. Dovecot
respectively OpenLDAP does not switch to another LDAP.

Best regards
Matthias
-- 
Matthias Egger
ETH Zurich
Department of Information Technology          maegger at ee.ethz.ch
and Electrical Engineering
IT Support Group (ISG.EE), ETL/F/24.1         Phone +41 (0)44 632 03 90
Physikstrasse 3, CH-8092 Zurich               Fax   +41 (0)44 632 11 95


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