[exim] LDAP failover

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Author: Christian Balzer
Date:  
To: exim-users
Subject: [exim] LDAP failover

Hello,

Exim 4.50 and OpenLDAP 2.2.23 (Debian Sarge).

I have a pair of LDAP servers for the various mail servers, that is I
HAD a pair. One of them expired (hardware failure) and this happened
to be the first one in the ldap_default_servers definition.
Which resulted in massive delays/timeouts until I manually changed
the sequence to have the working one first.

Now, I fully realize that exim doesn't keep a state of these things, but
maybe some sort of hinting mechanism would be a nice addition for the
future.

Am I correct in assuming that with my LDAP server defined (in DNS)
as a host with 2 IP addresses (and just one entry in exim.conf) I
would still have suffered delays, but 50% less on average?

I of course could turn LDAP into a HA service (already running
heartbeat for other services on these hosts in that mode), but I
preferred to do poor man's load balancing via the exim.conf LDAP
server ordering as opposed to an active/standby configuration.

So what I'm saying (again ;) is I'd like to see exim fail over
in a more semi-permanent way when trying to reach external
database servers like LDAP.

Dewa,

Chibi
-- 
Christian Balzer        Network/Systems Engineer                NOC
chibi@???       Global OnLine Japan/Fusion Network Services
http://www.gol.com/