The failures of the majority of nodes will affect the majority of replicas in some log streams.
When the majority of nodes fail, some log streams will lack a leader for a long period. In this case, it is the top priority to recover services. You must identify the cause of the failure as soon as possible and try to troubleshoot the issue. For example, you can check whether the node failure is caused by a network or hardware exception. If the majority of nodes fail due to clog deletion or hardware failures, you cannot perform ordinary O&M operations to restore the cluster. Instead, you can restore the cluster only by using a physical backup or initiating a failover of the physical standby database.