A Practical ClickHouse Monitoring Guide Built Around Failure Modes
Why does a ClickHouse cluster report every node as healthy while inserts start failing and dashboards go stale? Most often the failing subsystem was never represented in the metrics anyone had on screen. A node answers its health check while its replication queue has been growing for hours. ClickHouse breaks in specific, repeatable ways. Parts accumulate faster than background merges can consolidate them. Coordination drops quorum and every replicated table quietly turns read-only.