Upgrading dovecot 2.2 to 2.3 without downtime when using proxy/director?

[Niels Kobschätzki]

Hi,

I have a setup with several dovecot-servers (2.2.35) and I use dovecot
proxy. I upgraded one server to 2.3.1 and got the configs fixed so far
that it started again. But when I tried to add it into the proxying
again with "doveadm director add" I see the following in the logfiles:

May  6 07:19:30 host dovecot: director: Warning: Director
xxx.xxx.xxx.176:9090/out disconnected us with reason: Invalid input: OPTIONS
May  6 07:19:30 $host dovecot: director: Connecting to
xxx.xxx.xxx.171:9090 (as xxx.xxx.xxx.176): Reconnecting after error

xxx.xxx.xxx.176 is the upgraded host, xxx.xxx.xxx.171 is one of the
other hosts (the applicable hosts are in the range xxx.xxx.xxx.171-176).

Do I have to remove all the hosts from the proxy, upgrade them and then
add them again? Or is there a way to handle the upgrade without a
downtime? After all one of the reasons I use several hosts is that I do
not want to have a downtime.

Niels