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Managing a Multi-AZ deployment for RDS Custom for Oracle

In a Multi-AZ DB instance deployment for RDS Custom for Oracle, Amazon RDS automatically provisions and maintains a synchronous standby replica in a different Availability Zone (AZ). The primary DB instance is synchronously replicated across Availability Zones to a standby replica to provide data redundancy.

Running a DB instance with high availability can enhance availability during planned system maintenance. In the event of planned database maintenance or unplanned service disruption, Amazon RDS automatically fails over to the up-to-date standby DB instance. This functionality lets database operations resume quickly without manual intervention. The primary and standby instances use the same endpoint, whose physical network address transitions to the standby replica as part of the failover process. You don't have to reconfigure your application when a failover occurs.

The following diagram shows the Multi-AZ architecture for RDS Custom for Oracle:

You can create an RDS Custom for Oracle Multi-AZ deployment by specifying Multi-AZ when creating an RDS Custom DB instance. RDS Custom for Oracle DB instances created before June 30, 2025 cannot convert to Multi-AZ deployments by modifying the DB instance and specifying the Multi-AZ option. You have to create a new RDS Custom for Oracle DB instance by specifying the Multi-AZ option. New DB instances created using the service-provided AMI available after June 30, 2025 support the Multi-AZ option. Then, you have to migrate your existing RDS Custom for Oracle database to the newly created DB instance. For details, see Migration steps for DB instances using CEVs created before June 30, 2025.

The Amazon RDS console shows the Availability Zone of the standby replica (the secondary AZ). You can also use the describe-db-instances CLI command or the DescribeDBInstances API operation to find the secondary AZ.

RDS Custom for Oracle DB instances with Multi-AZ deployment can have increased write and commit latency compared to a Single-AZ deployment. This increase can happen because of the synchronous data replication between DB instances. You might have a change in latency if your deployment fails over to the standby replica, although Amazon is engineered with low-latency network connectivity between Availability Zones.

Region and version availability

Multi-AZ deployments for RDS Custom for Oracle are supported for the following Oracle Database editions:

Multi-AZ deployments for RDS Custom for Oracle are available in all Regions where RDS Custom for Oracle is available. For more information on Region availability of Multi-AZ deployments for RDS Custom for Oracle, see Supported Regions and DB engines for RDS Custom for Oracle.

Limitations for a Multi-AZ deployment with RDS Custom for Oracle

Multi-AZ deployments with RDS Custom for Oracle have the following limitations:

Creating an RDS Custom for Oracle DB instance with a Multi-AZ deployment

To create an RDS Custom for Oracle DB instance with a Multi-AZ deployment, follow the steps in Setting up your environment for Amazon RDS Custom for Oracle to setup your environment with the prerequisites.

You can create an RDS Custom for Oracle instance with a Multi-AZ deployment by choosing the Multi-AZ option during the database instance creation in the Amazon RDS console. Alternatively, you can specify the --multi-az parameter in the Amazon RDS create-db-instance command in the Amazon CLI.