When a primary/secondary failover occurs on your ApsaraDB MyBase for MySQL instance, Alibaba Cloud sends you an SMS notification that explains the reason for the failover. This topic describes the possible reasons.
A primary/secondary failover on an ApsaraDB MyBase for MySQL instance occurs for the following reasons:
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Vulnerability
When Alibaba Cloud detects a potential vulnerability that could affect the normal operation of an instance, the system patches the vulnerability on the secondary instance before initiating a primary/secondary failover during the configured maintenance window. For critical vulnerabilities, the system performs the fix and failover immediately to mitigate risk.
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Manual operation
You or an authorized Alibaba Cloud technical expert can manually initiate a primary/secondary failover.
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Instance failure
If Alibaba Cloud detects that the primary instance has failed, the system automatically initiates a primary/secondary failover to quickly restore service availability and minimize the impact of the failure.
After a primary/secondary failover is complete, the instance status changes to Running. No action is required, and the instance operates normally. You can view the Primary/Secondary Failover Log on the Service Availability page in the RDS console. For more information, see View primary/secondary failover logs. The log table includes the Failover Event ID, Start Time, End Time, and Reason columns. The reason in the log corresponds to one of the types described above, for example, "Manual Operation (triggered from the console or by an administrator)".