You have to design a disaster recovery plan for an application running on GCE and using Cloud Spanner. What is the most effective way to minimize RTO and RPO?

The most effective way to minimize RTO (Recovery Time Objective) and RPO (Recovery Point Objective) for an application using GCE and Cloud Spanner is to combine a Global Load Balancer with Multi-Regional Cloud Spanner. A Global Load Balancer provides a single, global IP address and automatically directs traffic to the nearest healthy GCE instances across multiple regions, ensuring high availability and low latency. Multi-Regional Cloud Spanner stores data redundantly across multiple geographical regions, offering strong consistency and automatic failover in case of a regional outage. This combination ensures that the application remains accessible and data is consistent even during significant regional disasters. Regional GCE instances + Regional Cloud Spanner would still be vulnerable to a regional outage. Global Load Balancer + Read replicas in secondary regions for Cloud Spanner would not provide strong consistency across regions. Regional GCE instances + Multi-Regional Cloud Spanner would still require manual intervention to redirect traffic to another region if the primary region fails. Zonal GCE instances + Zonal Cloud Spanner would be highly susceptible to zonal failures.