My Amazon Relational Database Service (Amazon RDS) DB instance failed over and I’m not sure why.
Short Description
If there's a planned or an unplanned outage for a Multi-AZ DB instance, Amazon RDS automatically switches to a standby replica or secondary instance in another Availability Zone. Depending on your database activity at the time of the outage, failover usually lasts between 60-120 seconds.
Resolution
To see if a failover has occurred, open the Amazon RDS console, and then choose Events from the navigation pane. Access events from the past 24 hours in the console. Or, use the describe-events command in the AWS Command Line Interface (AWS CLI). For more information, see Viewing Amazon RDS events.
Note: If you receive errors when running AWS CLI commands, make sure that you're using the most recent version of the AWS CLI.
There are several events that can cause a failover. When these types of unplanned outages occur, Amazon RDS monitors and identifies the issue. Then, Amazon RDS fails over automatically to minimize downtime.
Related Information
Best practices for Amazon RDS