Performing a Master/Standby Switchover for a DCS Instance

On the DCS console, you can manually switch the master and standby nodes of a master/standby or read/write splitting DCS instance. This operation is used for special purposes, for example, releasing all service connections or terminating ongoing service operations. When an instance is deployed across AZs, master/standby switchover can be performed to allow applications for nearby connections. For details, see Example Master/Standby Switchover Scenario.

The instance IP address does not change after a master/standby switchover, so the client does not need to change the connection address.

Example Master/Standby Switchover Scenario

The master node is in AZ A, the replica node is in AZ B, and the client ECS is in AZ B. Before master/standby switchover, the ECS connects to the master node across AZs. Cross-AZ connection is at higher latency. After the switchover, the master node and the ECS are in the same AZ B. The connection is near and at the lowest latency.

Click to enlarge

Notes and Constraints

The instance must be in the Running state.
This operation is unavailable for a cluster instance. To manually switch the master and replica nodes of a Proxy Cluster or Redis Cluster shard, use the node management function of the instance. For details, see Managing DCS Instance Shards and Replicas.

Impacts

During a master/standby switchover, services will be interrupted for up to 10 seconds. Before performing this operation, ensure that your application supports connection re-establishment in case of disconnection.
During a master/standby node switchover, a large amount of resources will be consumed for data synchronization between the master and standby nodes. You are advised to perform this operation during off-peak hours.
Data of the maser and standby nodes is synchronized asynchronously. Therefore, a small amount of data that is being operated on during the switchover may be lost.

Performing a Master/Standby Switchover for a DCS Instance

Log in to the DCS console.
Click in the upper left corner of the console and select the region where your instance is located.
In the navigation pane, choose Cache Manager.
In the Operation column of the instance, choose More > Master/Standby Switchover.
In the displayed dialog box, confirm the master/standby switchover and click OK.
The Background Tasks page is displayed. When the master/standby switchover task is in the Successful state, as shown in Figure 1.

Figure 1 Viewing the master/standby switchover status