Question about replication

[Coy Hile]

> On Aug 2, 2019, at 7:57 AM, Sami Ketola via dovecot <dovecot at dovecot.org> wrote:
> 
> 
> 
>> On 2 Aug 2019, at 14.52, Coy Hile via dovecot <dovecot at dovecot.org> wrote:
>> 
>> Good morning,
>> 
>> 
>> I’m looking at dovecot replication for the first time for a particular use case: The VM running dovecot is currently in a public cloud, and  I want to move it on-premises, so I want to replicate all mail data from the older instance to the new (then cutover internal DNS) (and in the process update to newer features on the internal instance such as mdbox vs Maildir).
>> 
>> However, the new instance I’m building is internal, would have access to the internet only via NAT, so the replication would have to be one way. Is there anything in particular that I need to keep in mind when I’m trying to setup this sort of setup? The documentation that I’ve read seems to imply (or assume) synchronous, bidirectional replication.
>> 
>> Thanks, and apologies if this is an obvious question; this is my first foray into doing something not utterly trivial with Dovecot.
> 
> Sounds like you do not want to do replication but migration.
> 
> In this case migration can be easily done by using doveadm dsync to pull the mails from old server to new server. 
> 
> Something like: 
> 
> doveadm backup -u userid -R -f ssh syncuser at remote "sudo /usr/bin/doveadm dsync-server -u userid”
> 

That may be the easier solution, you’re right. I was hoping to run both in parallel for a bit, but cutting over probably makes the most sense.

Thanks,

-Coy