MultiAZ

MultiAZ, short for multi-Availability Zone, is a cloud deployment pattern that distributes resources and data across multiple isolated data centers within a single geographic region. The goal is to improve availability and resilience by reducing the risk that a single data center outage will cause service interruptions or data loss.

In a typical MultiAZ setup, a primary resource runs in one Availability Zone while one or more redundant copies reside in different zones. For stateful services such as databases, replication is configured to maintain data consistency, often with synchronous replication to standby resources. Failover to a healthy replica in another zone can occur automatically when the primary component or its zone experiences a failure, helping to minimize downtime. To clients, the service endpoint usually remains the same, providing seamless continuity during failover.

Benefits of MultiAZ include higher availability, reduced recovery time in the event of failures, improved data durability, and easier maintenance through rolling updates without complete service downtime. It also supports disaster recovery planning within a single region and can enhance read scalability when replicas are used for read traffic.

Considerations and trade-offs include higher operational costs due to duplicate resources, potential cross-zone network latency and bandwidth charges, and increased architectural complexity. Some workloads or services may not require MultiAZ, and it should be complemented with cross-region disaster recovery for broader resilience. MultiAZ is a regional strategy and does not inherently protect against regional outages; for that, cross-region replication and backup solutions are needed.