Converting a DB instance to a Multi-AZ deployment for Amazon RDS - Amazon Relational Database Service
Convert to a Multi-AZ DB instance deployment with the RDS consoleModifying a DB instance to be a Multi-AZ DB instance deployment

Converting a DB instance to a Multi-AZ deployment for Amazon RDS

Modifying a DB instance to a Multi-AZ deployment improves availability by adding a standby instance in another Availability Zone. The process involves minimal downtime and requires careful planning around storage and performance impacts. This change enhances fault tolerance and reduces recovery time in case of failures, making it ideal for high-availability environments.

If you have a DB instance in a Single-AZ deployment and modify it to a Multi-AZ DB instance deployment, Amazon RDS performs the following actions:

  1. Takes a snapshot of the primary DB instance's Amazon Elastic Block Store (EBS) volumes.

  2. Creates new volumes for the standby replica from the snapshot. These volumes initialize in the background, and maximum volume performance is achieved after the data is fully initialized.

  3. Turns on synchronous block-level replication between the volumes of the primary and standby replicas.

Important

Creating a standby DB instance from a snapshot during a Single-AZ to Multi-AZ conversion avoids downtime but might impact performance, particularly for write-sensitive workloads. The synchronous replication can increase I/O latency, affecting database performance. As a best practice, avoid converting a production DB instance to a Multi-AZ DB instance.

Instead, create a read replica, enable backups on it, convert it to Multi-AZ, load data into its volumes, and then promote it to the primary DB instance. For more information, see Working with DB instance read replicas.

There are two ways to modify a DB instance to be a Multi-AZ DB instance deployment:

Convert to a Multi-AZ DB instance deployment with the RDS console

You can use the RDS console to convert a DB instance to a Multi-AZ DB instance deployment.

You can only use the console to complete the conversion. To use the AWS CLI or RDS API, follow the instructions in Modifying a DB instance to be a Multi-AZ DB instance deployment.

To convert to a Multi-AZ DB instance deployment with the RDS console

  1. Sign in to the AWS Management Console and open the Amazon RDS console at https://console.aws.amazon.com/rds/.

  2. In the navigation pane, choose Databases, and then choose the DB instance that you want to modify.

  3. From Actions, choose Convert to Multi-AZ deployment.

  4. On the confirmation page, choose Apply immediately to apply the changes immediately. Choosing this option doesn't cause downtime, but there is a possible performance impact. Alternatively, you can choose to apply the update during the next maintenance window. For more information, see Using the schedule modifications setting.

  5. Choose Convert to Multi-AZ.

Modifying a DB instance to be a Multi-AZ DB instance deployment

You can modify a DB instance to be a Multi-AZ DB instance deployment in the following ways:

  • Using the RDS console, modify the DB instance, and set Multi-AZ deployment to Yes.

  • Using the AWS CLI, call the modify-db-instance command, and set the --multi-az option.

  • Using the RDS API, call the ModifyDBInstance operation, and set the MultiAZ parameter to true.

For information about modifying a DB instance, see Modifying an Amazon RDS DB instance. After the modification is complete, Amazon RDS triggers an event (RDS-EVENT-0025) that indicates the process is complete. You can monitor Amazon RDS events. For more information about events, see Working with Amazon RDS event notification.