Minimum master nodes below quorum
discovery.zen.minimum_master_nodes is set below a safe majority of master-eligible nodes. On clusters that still use this legacy Zen discovery setting, that weakens protection against split brain if the cluster partitions.
For a complete list of insights, refer to AutoOps insights.
| Field | Value |
|---|---|
| Component | Elasticsearch |
| Severity | High |
| Scope | Cluster |
| Domains | configuration, high-availability, stability |
The following is an example of what you might see when this insight is triggered. Real insights use live data and links from your deployment or cluster.
discovery.zen.minimum_master_nodes is es-data-01. The cluster has 12 master-eligible nodes.
AutoOps shows different recommendations depending on how their conditions match your deployment or cluster.
Set minimum master nodes quorum
Condition: Always shown for this insight.
Set discovery.zen.minimum_master_nodes to 2 in each node's config, then rolling-restart master-eligible nodes so the quorum takes effect.
discovery.zen.minimum_master_nodes is the legacy Zen discovery quorum setting. It applied on older Elasticsearch versions that used Zen Discovery to elect a master. Modern Elasticsearch uses automatic voting configuration instead, but this setting can still appear on upgraded clusters or legacy deployments.
When the value is below half of master-eligible nodes, rounded up, a network partition can let disconnected nodes form a second cluster with its own master. Split brain can cause conflicting writes and data loss.