- Stefan G. Weichinger:
does it make sense in this case to set up replication and let the servers replicate at first while still running on the old server?
If you use "dsync over TCP connections" [1], you can set up your new server without users noticing it (with the exception of extra server load for replication). It will take some time to sync all the data, but it takes no manual action once replication is fully set up.
[1] https://wiki.dovecot.org/Replication
The docs state one should be able to use a "noreplicate" field to limit the accounts, but I was not able to get it to work with a LDAP user DB. Regardless what value I provided in LDAP, replication would happen, and I could not find detailed documentation.
do I have advantages over doing some rsync-jobs?
Oh, you know, some small stuff, like data integrity checks, retry on failures, event-driven replication. ;-)
-Ralph