An active-active cluster refers to a cluster containing two availability zones (usually independent data centers). These two availability zones can independently provide computing and storage services, typically located in the same geographical area. This setup ensures that if one availability zone fails, data can be recovered from the other availability zone, guaranteeing service continuity. When both availability zones are operating normally, the cluster stores each data block in two availability zones using a 3-replica scheme, with two replicas in one availability zone and one replica in the other. When one availability zone fails, the complete data can still be retrieved from the surviving zone to restore services.
