dovecot - Feb 2008 - Dovecot pgsqlauthentication database reconnection/failover problem

Hi,
    Our mail system uses dovecot-1.0-1.2.rc15.el5 in Centos-5.1 as our imap 
server. It connects to a pgsql database in another server as authentication 
backend. It works fine except occasionally fails to reconnect to the database 
after temporary network block, and dovecot has to be restarted to work again 
in such case. Since I can't find any specific setting in dovecot.conf to 
handle this reconnection problem, I opt to build a failover pgsql backend. 
Google led me to  
http://www.dovecot.org/list/dovecot/2008-January/027899.html.  I followed the 
thread to modify my dovecot-sql.conf containing "connect = host=pgsql1 
host=pgsql2 dbname=xxxx user=xxxx"
   If both databases are available, dovecot will choose pgsql2 as the default 
one, and user login works flawlessly. But when I block all traffic to host 
pgsql2, dovecot will repeatedly try pgsql2 and neglect available host pgsql1. 
   I don't find relevent information in the dovecot wiki either. Can anyone 
here shed a light on me?
    Thanks in advance!

Regards, 
Frank Wang

On Sat, 2008-02-16 at 21:46 +0800, Frank Wang wrote:
> Hi,
>     Our mail system uses dovecot-1.0-1.2.rc15.el5 in Centos-5.1 as our imap
> server. It connects to a pgsql database in another server as authentication
> backend. It works fine except occasionally fails to reconnect to the
database
> after temporary network block, and dovecot has to be restarted to work
again
> in such case. 
It's most likely fixed in newer versions. For example there is one
PostgreSQL fix in v1.0.4 and another in v1.0.rc26. There may be other
fixes as well.

You can find newer Dovecot RPMs for CentOS 5 from atrpms.net.
> Google led me to  
> http://www.dovecot.org/list/dovecot/2008-January/027899.html.  I followed
the
> thread to modify my dovecot-sql.conf containing "connect = host=pgsql1
> host=pgsql2 dbname=xxxx user=xxxx"
Currently this works only with MySQL.
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> On Sat, 2008-02-16 at 21:46 +0800, Frank Wang wrote:
> > Hi,
> >     Our mail system uses dovecot-1.0-1.2.rc15.el5 in Centos-5.1 as our
> > imap server. It connects to a pgsql database in another server as
> > authentication backend. It works fine except occasionally fails to
> > reconnect to the database after temporary network block, and dovecot
has
> > to be restarted to work again in such case.
>
> It's most likely fixed in newer versions. For example there is one
> PostgreSQL fix in v1.0.4 and another in v1.0.rc26. There may be other
> fixes as well.
>
> You can find newer Dovecot RPMs for CentOS 5 from atrpms.net.
>
Thanks for the quick reply.
I've tested the  dovecot-1.0.10-0_66.el5 from atrpms.net. The reconnection 
problem hasn't occur during the test so far, good!  I'll need sometime
to
test the stability though, as it's marked test in the repo. 
> > Google led me to
> > http://www.dovecot.org/list/dovecot/2008-January/027899.html.  I
followed
> > the thread to modify my dovecot-sql.conf containing "connect >
> host=pgsql1 host=pgsql2 dbname=xxxx user=xxxx"
>
> Currently this works only with MySQL.
Is it possible to achieve similar failover using pgsql backend? As we had 
built other systems using the same pgsql database, migrate to mysql is not an 
option here.

Regards,
Frank Wang