Disaster Recovery and Multi-Active Solution

Single-AZ HA

Single-AZ deployment means to deploy an instance within a physical equipment room. DCS provides process/service HA, data persistence, and hot standby DR policies for different types of DCS instances.

Single-node DCS instance: When DCS detects a process fault, a new process is started to ensure service HA.

Figure 2 HA for a single-node DCS instance deployed within an AZ

By default, instances except for single-node ones support data persistence. Data is persisted to disk in the master node and incrementally synchronized and persisted to the standby node, achieving hot standby and persistent data backups.

For master/standby instances, and each shard of cluster instances, the master node process synchronizes and persists data to the standby node processes, as shown in the following figure.

Figure 3 HA for a master/standby DCS instance deployed within an AZ

Cross-AZ DR

The master and standby nodes of a master/standby or cluster DCS instance can be deployed across AZs (in different equipment rooms). Power supplies and networks of different AZs are physically isolated. When a fault occurs in the AZ where the master node is deployed, the standby node connects to the client and takes over data read and write operations.

Figure 4 Cross-AZ deployment of a master/standby DCS instance

Figure 5 Cross-AZ deployment of a Proxy Cluster DCS instance

Figure 6 Cross-AZ deployment of a Redis Cluster DCS instance

When creating a master/standby, or cluster DCS instance, select a standby AZ that is different from the primary AZ.

Figure 7 Selecting different AZs

• You can deploy your application across AZs to ensure both data reliability and service availability in the event of power supply or network disruptions.
• Cross-AZ instances do not support password changes, command renaming, and specification modification when an AZ is faulty.