etcd database backs Kubernetes control plane state, so if the etcd service is unavailable, the Kubernetes control plane goes down, and the cluster is not recoverable until etcd is recovered. etcd builds around the consensus protocol Raft, so highly-available control plane clusters can tolerate the loss of nodes so long as more than half of the members are running and reachable. For a three control plane node Talos cluster, this means that the cluster tolerates a failure of any single node, bu...