I am going to deploy openstack multi regions and I know that keystone replication is the most challenging.

I plan to set up 2 regions which use centralize galera cluster(3 nodes). and one standby edge galera cluster(3 nodes)

When region 1 is node available, I will map region 2 to use standby edge galera cluster.

I hope  you give me some experience and advice with multi regions.

Thank you very much.