When Does a Master/Standby Switchover Occur?

A master/standby switchover may occur in the following scenarios:

• A master/standby switchover operation is initiated on the DCS Console.
• A master/standby switchover will be triggered when the master node of a master/standby instance fails.

  For example, if commands (such as KEYS) that consume a lot of resources are used or logs are aged and deleted in batches, the CPU usage will surge, triggering a master/standby switchover.

• If you restart a master/standby instance on the DCS console, a master/standby switchover will be triggered.
• If you scale up a single-node, read/write splitting, or master/standby instance, a master/standby switchover will be triggered.

  During scale-up, a new standby node with the new specifications is created. After full and incremental data on the master node is synchronized to the standby node, a master/standby switchover is performed and the original node is deleted.

After a master/standby switchover occurs, you will receive a notification. Check whether the client services are running properly. If not, check whether the TCP connection is normal and whether it can be re-established after the master/standby switchover to restore the services.