Resolve Incompatible Parameters Error | RDS MySQL Reboot Failure Troubleshooting | AWS Certified Database Specialty Exam

Answer: D.

Option A is incorrect because AWS RDS does not allow modification of MySQL system variables directly using the SET statement.

Instead, DB parameter groups must be used.

Option B is incorrect because you cannot modify the default DB parameter group values.

Option C is incorrect because you cannot modify the RDS instance in an incompatible parameters state.

You must reset the values of the DP parameter group currently applied to the RDS instance.

Option D is CORRECT because one (or more) parameters are set to non-default values that are not compatible with the current RDS engine or instance class.

To resolve the issue, you must reset the parameters to their default values.

Reference:

https://aws.amazon.com/premiumsupport/knowledge-center/rds-incompatible-parameters/

The error message "MySQL could not be started due to incompatible parameters" indicates that the MySQL server on the RDS MySQL database instance was unable to start due to some incompatible configuration parameters. To resolve this issue, you need to identify the root cause of the problem and take appropriate actions.

There are several possible reasons for this error, but one common cause is that some custom system variables were modified to values that are not compatible with the MySQL version or configuration. To address this issue, you can use the following steps:

Option A: Use SELECT and SET statements to identify and reset custom system variables to default values.

• Use the following SQL statement to identify any modified system variables and their values: SELECT VARIABLE_NAME, SESSION_VALUE, GLOBAL_VALUE FROM performance_schema.global_variables WHERE SESSION_VALUE != GLOBAL_VALUE;
• Review the results and identify any variables that have custom values.
• Use the SET statement to reset any modified system variables to their default values: SET GLOBAL variable_name=DEFAULT;
• Reboot the RDS instance and verify that the issue is resolved.

Option B: Reset the RDS instance's parameter group to default values.

• In the RDS console, select the affected RDS instance.
• Navigate to the "Configuration" section and select the "Parameter groups" tab.
• Select the default DB parameter group for your MySQL engine version.
• Choose the "Reset Parameter Group" action to revert all parameters to their default values.
• Reboot the RDS instance and verify that the issue is resolved.

Option C: Modify the RDS instance to use the default parameter group and reboot it.

• In the RDS console, select the affected RDS instance.
• Navigate to the "Configuration" section and select the "Parameter groups" tab.
• Select the default DB parameter group for your MySQL engine version.
• Choose the "Apply Immediately" action to apply the parameter group to the RDS instance.
• Reboot the RDS instance and verify that the issue is resolved.

Option D: Compare the RDS instance's parameter group to the default parameter group and reset any custom parameters to their default values.

• In the RDS console, select the affected RDS instance.
• Navigate to the "Configuration" section and select the "Parameter groups" tab.
• Select the RDS instance's parameter group and compare it to the default DB parameter group.
• Identify any parameters that have custom values.
• Reset any custom parameters to their default values.
• Reboot the RDS instance and verify that the issue is resolved.

In summary, to resolve the error "MySQL could not be started due to incompatible parameters" on an RDS MySQL database instance, you need to identify the root cause of the problem and take appropriate actions, such as resetting modified system variables to default values or resetting the parameter group to default values.