How do I create a read replica for an Amazon RDS DB instance?

Resolution

To create a read replica, complete the following steps based on your engine type:

• If you use Amazon Relational Database Service (Amazon RDS) for MariaDB, then see Working with MariaDB read replicas.
• If you use Amazon RDS for Microsoft SQL Server, then see Working with read replicas for Microsoft SQL Server in Amazon RDS.
• If you use Amazon RDS for MySQL, then see Working with MySQL read replicas.
• If you use Amazon RDS for Oracle, then see Working with read replicas for Amazon RDS for Oracle.
• If you use Amazon RDS for PostgreSQL, then see Working with read replicas for Amazon RDS for PostgreSQL.

Use cases for read replicas

To assist with large workloads

Use read replicas to scale beyond the compute or I/O capacity of a single DB instance for read-heavy database workloads. You can direct this excess read traffic to one or more read replicas.

To serve read traffic while the DB instance is unavailable

Use read replicas to serve read traffic when the source DB instance isn't available. Your source DB instance might not be available to take I/O requests, for example, because of I/O suspension for backups or scheduled maintenance. If your source DB instance isn't available to take requests, then you can direct read traffic to your read replicas.

Note: Because the source DB instance is unavailable, the data on the read replica might be stale.

For business reporting or data warehousing scenarios

Use read replicas for business reporting or data warehousing scenarios to run business reporting queries against a read replica instead of your production DB instance.

For disaster recovery

Use read replicas to implement disaster recovery. Promote a read replica to a standalone instance as a disaster recovery solution if the primary DB instance fails.

Best practices for read replicas

Use read replicas in different Regions to improve response times

To improve client response times in different geographic locations, use read replicas in different AWS Regions. For more information, see Creating a read replica in a different AWS Region.

Use High availability (Multi-AZ) for Amazon RDS

Because replica creation can lead to I/O latency, it's a best practice to create read replicas when you anticipate a light database load. To mitigate I/O latency on your source DB instance and during read replica setup, use high availability (Multi-AZ) for Amazon RDS.

Mirror the source database

For optimal performance, the read replica must mirror the source database. If you use the Amazon RDS console to create a read replica, the console applies the source database settings by default.

Related information

Working with DB instance read replicas