Indices without replicas
One or more indices on hot, warm, content, or generic data nodes are configured with no replica shards. If a primary fails or data is corrupted, there is no promoted copy to keep the index online.
For a complete list of insights, refer to AutoOps insights.
| Field | Value |
|---|---|
| Component | Elasticsearch |
| Severity | High |
| Scope | Index |
| Domains | performance, cluster-health, replication, stability |
You can customize these settings to adjust when AutoOps detects this event and presents the insight. Refer to AutoOps event settings for details.
The default customization settings are:
| Setting | Type | Default |
|---|---|---|
| Exclude indices based on this pattern | List of strings | |
| Data roles (tiers) to exclude from indication | List of strings | data_frozen,data_cold |
| Don't raise event if the index is smaller than (MB) | Integer | 0 |
| How long after index creation do you want to postpone this event trigger? (In min) | Integer | 5 |
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.
At least 12 indices have no replicas, a sample is listed below.
Affected indices: logs-prod-000045, logs-prod-000046
AutoOps shows different recommendations depending on how their conditions match your deployment or cluster.
Add data node
Condition: Shown when only one data node available.
Add a data node to increase capacity and reduce pressure on the existing nodes.
Increase replica count
Condition: Shown when index has no replica shards and enough data nodes are available.
Set number_of_replicas to 1 on logs-prod-000045 (currently 2) using the action below.
PUT logs-prod-000045/_settings
{
"index": {
"number_of_replicas": 1
}
}
Requires the manage index privilege. Requires Elasticsearch 8.0.0 or later. This action changes cluster or index configuration.
Replica shards provide resilience and load sharing on tiers that serve frequent reads and writes. If a primary shard fails or data is corrupted, a replica can be promoted so the index stays searchable and writable. Without replicas, recovery depends on restoring from snapshots or waiting for the primary to return.
Replicas also give Elasticsearch alternate copies for search routing. When a node is under load and an index has no replicas, searches for shards on that node must wait because there is no other node to serve the data.
This insight focuses on indices whose shards sit on hot, warm, content, or generic data nodes, where Elastic typically recommends keeping at least one replica. Cold and frozen tiers are excluded by default. Those tiers often use searchable snapshots, so zero replicas is a common cost and capacity choice rather than a misconfiguration. You can change which tiers are excluded in the insight settings.