Hi Kota,
Thanks for your questions!
> - Are there any circumstances where the target (MSK) offsets could be
> overwritten by smaller source offsets while consumers are already running
> on MSK?
> - I assume that this kind of behavior is not intended by design.
No, as soon as you start the first consumer on the target cluster, MM2
offset syncing will stop for that group and offsets can only be changed by
the target consumers. This is a property enforced by the consumer group
coordinator, not a MM2 feature specifically.
However, it is extremely likely that the target consumer will get some
messages that already had offsets committed by the source consumers, even
if you stop the source consumers first. Your consumer application should be
able to tolerate this re-delivery if you want to do a live/staged migration
(consumers before producers) like you described.
> - Will new messages written to onpre-kafka continue to replicate to MSK
> ...