ZooKeeper Connection Issues in Replicated Setup

critical

reliabilityUpdated Feb 6, 2026

ZooKeeper connectivity problems or high request latency disrupt replication coordination, causing replica lag, failed writes, or split-brain scenarios.

Sources

How to Monitor ClickHouse Query Performance with OpenTelemetryoneuptime.com

Technologies:

ClickHouseSymptoms of this issue are visible in ClickHouse metrics and logs

clickhouse.zookeeper.session_expired

How to detect:

Monitor ZooKeeperRequest and ZooKeeperWatch metrics from ClickHouse. Alert on ZooKeeper session expiration, high request rates (>1000/sec), or latency spikes in ZooKeeper operations.

Recommended action:

Check ZooKeeper cluster health and network connectivity, review ZooKeeper logs for errors, increase ZooKeeper timeout settings if network is slow, scale ZooKeeper ensemble if overloaded, or migrate to ClickHouse Keeper for better integration.