ApsaraDB RDS:Switch workloads over between primary and secondary ApsaraDB RDS for SQL Server instances

Limits

Serverless RDS instances do not support manual primary/secondary switchovers. For more information, see Overview. If a serverless RDS instance fails, the system automatically switches workloads over between primary and secondary serverless RDS instances.

Usage notes

The primary/secondary synchronization mechanism of ApsaraDB RDS for SQL Server ensures full data synchronization between the primary RDS instance and secondary RDS instance of your database system. However, not all parameter settings of the ALTER LOGIN statement are synchronized. Only the settings of the SID, login_name, and password parameters in the ALTER LOGIN statement are synchronized. ApsaraDB RDS for SQL Server uses the default values for all the other parameters in the ALTER LOGIN statement. For more information, see ALTER LOGIN (Transact-SQL).

Impacts

• A service interruption that usually lasts less than 30 seconds occurs during a primary/secondary switchover. Make sure that your application is configured to automatically reconnect to your database system.

  If your application uses an earlier version of the Druid component for connection management, your application may fail to automatically reconnect to your database system after disconnection. We recommend that you upgrade the Druid component to 1.1.16 or later to resolve this issue.

• After a primary/secondary switchover, the read-only RDS instances that are attached to the primary RDS instance must re-establish the connections that are used to replicate data to and synchronize incremental data from the primary RDS instance. As a result, the data on the read-only RDS instances shows latencies of a few minutes.

• A primary/secondary switchover does not cause changes to the endpoints that are used to connect to your RDS instance. However, the IP addresses that are associated with the endpoints may change. If your application uses endpoints to connect to your RDS instance, your application can still run as expected after a primary/secondary switchover.

• A switchover may take longer when an instance fails.

Perform a manual primary/secondary switchover

1. Go to the Instances page. In the top navigation bar, select the region in which the RDS instance resides. Then, find the RDS instance and click the ID of the instance.

2. In the left-side navigation pane, click Service Availability.

3. In the Availability Information section of the page that appears, click Switch Primary/Secondary Instance.

4. Specify the time at which you want to perform a primary/secondary switchover. Then, click OK.

   Note

   You cannot perform specific operations during a primary/secondary switchover. For example, you cannot manage databases and accounts or change the network type. We recommend that you select Within Specified Time Range.

Disable automatic primary/secondary switchovers for a short period of time

View primary/secondary switchover logs

1. Go to the Instances page. In the top navigation bar, select the region in which the RDS instance resides. Then, find the RDS instance and click the ID of the instance.

2. In the left-side navigation pane, click Service Availability.

3. In the Primary/Secondary Switching Logs section of the page that appears, select a time range and view the primary/secondary switchover logs that are generated over the selected time range.

   

FAQ

• Do I need to manually switch my workloads over from the secondary RDS instance to the primary RDS instance after a primary/secondary switchover?

  No, you do not need to manually switch your workloads over from the secondary RDS instance to the primary RDS instance after a primary/secondary switchover. The data in the primary RDS instance is the same as the data in the secondary RDS instance. After a primary/secondary switchover, the secondary RDS instance serves as the new primary RDS instance. No additional operations are required.

• Each time a primary/secondary switchover is performed, my RDS instance does not run as expected 10 minutes after the primary/secondary switchover is complete. What are the possible causes? How do I handle the issue?

  If an exception on your RDS instance triggers a primary/secondary switchover to ensure high availability, your application may fail to identify and respond to the changes to the connections. If no timeout periods are specified for socket connections, your application waits for the database to return the results. In most cases, your application is disconnected after hundreds of seconds. During this period, some connections to the database cannot work as expected, and a large number of SQL statements fail to be executed. To avoid invalid connections, we recommend that you configure the connectTimeout and socketTimeout parameters to prevent your application from waiting for a long period of time due to network errors. This reduces the time required to recover from failures.

  You must configure these parameters based on your workloads and usage modes. For online transactions, we recommend that you set the connectTimeout parameter to 1 to 2 seconds and the socketTimeout parameter to 60 to 90 seconds. This configuration is for reference only.

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