Newbie question about replication

[John Fawcett]

On 16/10/2020 14:23, Piotr Auksztulewicz wrote:
> Hi,
>
> I am a long-time dovecot user/admin for my family mail server, but
> I had ventured into configuring replication only recently and I am not
> sure about how it should work and what are the good practices. My intent
> for replication was to have another instance to switch to in a short
> time if something fails. I have daily backups, but it will take much
> more time to rebuild and restore than just to switch to a good instance
> while taking time to restore the bad one.
>
> The setup seems to work just fine from IMAP client point of view (minus
> sieve scripts - but I have worked it around as I am not yet ready to
> upgrade dovecot beyond what's in stable Debian at the moment). I have my
> clients configured to access instance A exclusively; instance B is just
> sitting around with no clients routinely connected. Also only instance A
> is receiving deliveries from both my primary and secondary MTAs. I have
> some doubt however if this is the right thing to do and if it is correct
> from the dovecot server point of view.
>
> I have observed my mail storage directories on both instances and have
> noticed that they diverge a little over time - the instance B not having
> all the updates. However the moment I connect another client to instance
> B and log in as a particular user, the state on instance B springs to the
> correct state and I see the same content on both clients, and the storage
> directories become identical as well.

Are there any replication errors logged? Does

doveadm replicator status

or

doveadm replicator status <mailbox>

give any sign of errors?

Can you give some example or evidence of the disalignment that is happening?

John