With new support for cross-region disaster recovery in vCore-based Azure Cosmos DB for MongoDB, you can create a replica of a cluster in another region. This cluster replica is continuously updated with the data written in the primary region. In the rare case of an outage in the primary region, you can promote this replica to become the new read-write cluster.
You can also use the cluster replica in another region for reading. This helps offload read operations from the primary cluster and deliver reads with lower latency to applications that are hosted closer to the other region.
When the cluster replica in region B is promoted and becomes the new read-write cluster, it mirrors the original configuration by maintaining a read replica in the former primary region A. The global read-write connection string always points to the cluster available for writes. It allows uninterrupted work with the database after replica cluster promotion.