This topic describes how to view the data replication mode between a primary ApsaraDB RDS for SQL Server instance and its secondary ApsaraDB RDS for SQL Server instance.
Limits
The RDS instance runs RDS High-availability Edition or RDS Cluster Edition. For more information, see RDS High-availability Edition and RDS Cluster Edition.
You cannot change the data replication mode of the RDS instance.
Data replication modes
Synchronous mode
After an update that is initialized by your application is complete on a primary RDS instance, the log is synchronized to the secondary RDS instance. After the secondary RDS instance receives the log, the update transaction is considered committed. Your database system does not need to wait for the log to be replayed.
If a secondary RDS instance is unavailable or the communication between a primary RDS instance and a secondary RDS instance is abnormal, the synchronous mode degrades to the asynchronous mode.
Asynchronous mode
After an add, delete, or modify operation originated from an application is complete on a primary RDS instance, the primary RDS instance immediately responds to the application. At the same time, the primary RDS instance asynchronously replicates the added, deleted, or modified data to the secondary RDS instance of the primary RDS instance. In asynchronous mode, the workloads on the primary RDS instance run as expected even if the secondary RDS instance is unavailable. However, if the primary RDS instance is unavailable, errors may occur due to data inconsistencies between the primary RDS instance and the secondary RDS instance.
View the data replication mode of an RDS instance
- 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.
In the left-side navigation pane of the page that appears, click Service Availability to view the data replication mode of the RDS instance.