Changing the Failover Priority

Scenarios

RDS gives you control over the failover priority of your primary/standby DB instance. You can set it to Reliability or Availability.

• Reliability (default setting): Data consistency is preferentially ensured during a primary/standby failover. This is recommended for applications whose highest priority is data consistency.
• Availability: Database availability is preferentially ensured during a primary/standby failover. This is recommended for applications that require databases to provide uninterrupted online services.

Primary/Standby Replication Mode

• RDS for SQL Server uses synchronous replication between primary and standby instances by default. For SQL Server 2017 Enterprise Edition, the AlwaysOn mechanism is used. For other editions, database mirroring is used.
• RDS for SQL Server uses asynchronous replication between the primary DB instance and read replicas by default.

Procedure

1. Log in to the management console.
2. Click in the upper left corner and select a region and a project.
3. Click in the upper left corner of the page and choose Database > Relational Database Service.
4. On the Instances page, click the primary instance name.
5. On the displayed Basic Information page, find Failover Priority and click Change. In the displayed dialog box, select a priority and click OK.
6. View the result of the change on the Basic Information page.