How do I troubleshoot unexpected restarts or failovers for my Aurora MySQL-Compatible DB instances?

Short description

Unexpected restarts of Aurora MySQL-Compatible DB instances can occur because of the following reasons:

• Resource contentions and high workloads
• Minor version or patch upgrades and underlying operating system (OS) patches
• Manual reboots and database engine restarts
• Infrastructure issues
• Excessive workload
• Vertical scaling
• Maintenance requirements

To make sure that your DB instance continues operations, Aurora fails over to the read replica that has the highest priority or lowest numbered tier. For more information, see Fault tolerance for an Aurora DB cluster.

Resolution

Important: Performance Insights will reach its end of life on June 30, 2026. You can upgrade to the Advanced mode of Database insights before June 30, 2026. If you don't upgrade, then DB clusters that use Performance Insights will default to the Standard mode of Database Insights. Only the Advanced mode of Database Insights will support execution plans and on-demand analysis. If your clusters default to the Standard mode, then you might not be able to use these features on the console. To turn on the Advanced mode, see Turning on the Advanced mode of Database Insights for Amazon RDS and Turning on the Advanced mode of Database Insights for Amazon Aurora.

Resource contentions and high workloads

If an unexpected restart occurs because of resource contention, such as low available memory or high CPU usage, then take the following actions:

• Use Amazon CloudWatch to proactively monitor your Aurora MySQL-Compatible DB instance resource metrics. Set up CloudWatch alarms to notify you when the resource usage exceeds the defined thresholds.
• Use Amazon RDS Enhanced Monitoring to monitor memory usage, disk I/O, and CPU utilization at the OS level.
• Use the database load (DB load) chart in Performance Insights to identify and optimize resource-intensive queries. Then, review your application's database usage patterns.

If your workload consistently consumes a high amount of resources, then scale up to a larger instance type with more CPU, memory, or storage capacity. Optimize the queries and workload for your database instance. For example, use caching or other query optimization techniques to reduce the load on your DB instance.

Minor version or patch upgrades and underlying OS patches

To keep your DB instance in good operations, Aurora performs maintenance on your instance during your cluster maintenance window. This maintenance can include minor version or patch upgrades and and underlying OS patches. If an unexpected restart occurs during your cluster maintenance window, then the restart might be part of a planned system update or maintenance task. To prevent future unexpected restarts or failovers, adjust your maintenance window.

Manual reboots and database engine restarts

To better troubleshoot the restart issue, you must find out why an unexpected restart occurred. Check the Amazon Relational Database Service (Amazon RDS) events at the time of the restart. Or, you can use AWS CloudTrail to check the API calls for the event history. You can also review the database error logs to view the root cause of the unexpected restart. Look for any error messages or warnings related to resource contention, system issues, or other potential causes at the time of the restart.

Additional troubleshooting steps

For additional troubleshooting steps, you can review the release notes for Aurora MySQL-Compatibles patches. The release notes contain all the fixes for issues that are present in earlier versions of Aurora MySQL-Compatible. If you use a later version, then look for any issues that are similar to the root cause of the unexpected restart.