dovecot - Jan 2009 - behavior of dovecot with Openldap

Dear team,

I'm sorry if this is a stupid question, but I'd like to know the
behavior
of dovecot in a particular stuation. My questions are as follows.

In /etc/dovecot-ldap.conf, 'hosts=' field is the one which can be used
to specify availabled ldap server to access from the clients to authorize.
And also sevral ldap servers can be specified in 'hosts =' field as
shown
like below.

hosts = ldap-server1.example.com ldap-server2.example.com

?both server have the same configuration and available to replication
ldap-server1(master) to ldap-server2(slave).

If this is right, how does dovecot know which ldap server is currently used?
and if the master dies, how does dovecot know and switch to slave one?
In addition, which one is the exact behavior of dovecot in case master
server
dies?

1. only swithcing to the slave server
2. switching to the slave server, and once the master server is reactive
then
switch back to the master server automatically

OS?RHEL4 U3
kernel 2.6.9-34.ELsmp
openldap-2.2.13-12.el4

Thanks in advance,


Masaharu Kawada

-------------------
Masaharu Kawada
Associate Global Support Engineer
Red Hat K K
Ebisu Neonato 8F
1-18 Ebisu 4-chome, Shibuya-ku
Tokyo 150-0013, Japan
Direct: +81-3-5798-8482

On Jan 19, 2009, at 3:04 AM, Masaharu Kawada wrote:
> In /etc/dovecot-ldap.conf, 'hosts=' field is the one which can be
used
> to specify availabled ldap server to access from the clients to  
> authorize.
> And also sevral ldap servers can be specified in 'hosts =' field as
> shown
> like below.
>
> hosts = ldap-server1.example.com ldap-server2.example.com
Dovecot simply passes these servers to the OpenLDAP library. It  
doesn't do anything with them itself.
> ?both server have the same configuration and available to  
> replication
> ldap-server1(master) to ldap-server2(slave).
>
> If this is right, how does dovecot know which ldap server is  
> currently used?
> and if the master dies, how does dovecot know and switch to slave one?
I'm pretty sure that configuration will simply use both the servers  
all the time more or less randomly. Unless OpenLDAP library has some  
code that does something similar to what you're talking about, but  
somehow I doubt that.