Charmed MySQL K8s How-to - Async: Switchover / Failover

Switchover / Failover of Async replication

WARNING: it is an ‘8.0/edge’ article. Do NOT use it in production!
Contact Canonical Data Platform team if you are interested in the topic.

Pre-requisits

Make sure both Rome and Lisbon Clusters are deployed using the Async Deployment manual!

Switchover (safe)

Assuming Rome is currently Primary and you want to promote Lisbon to be new primary
(Rome will be converted to StandBy member):

juju run -m lisbon db2/leader promote-to-primary 

Failover (forced)

Warning: this is a dangerous operation which can cause the split-brain situation.
It should be executed if Primary cluster is NOT recoverable any longer!
Otherwise please use safe ‘switchover’ procedure above!

Assuming Rome was a Primary (before we lost the cluster Rome) and you want to promote Lisbon to be the new primary:

juju run -m lisbon db2/leader promote-to-primary force=True

Warning: The force will cause the old primary to be invalidated.