[openstack][largescale-sig] Openstack multi region deployment

Hello guys, 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.