Elasticsearch Cluster Health 101: Understanding Your Distributed System's Vital Signs You ship your Elasticsearch cluster to production. Traffic hits it. Three hours later, your monitoring dashboard flashes yellow. Your heart sinks. What does that mean? Are you in trouble? Should you wake up the on-call engineer at 2 AM? This post teaches you to read your cluster's health like a doctor reads vital signs. By the end, you'll understand what GREEN, YELLOW, and RED actually mean, why your cluster sometimes needs time to heal itself, and how to spot real problems before they become disasters. What Is Cluster Health? The Three States Every Elasticsearch cluster has a health status. It's not a guess. It's a concrete signal that tells you whether your data is safe.…