---
title: Unbalanced shard counts
description: Describes what AutoOps detects and surfaces with the Unbalanced shard counts insight: Shard counts across data nodes are skewed enough that some nodes carry far fewer shards than peers in the same tier.
url: https://docs-v3-preview.elastic.dev/elastic/autoops-insights/tree/main/elasticsearch/unbalanced_shard_counts
products:
  - Elastic Cloud Enterprise
  - Elastic Cloud Hosted
  - Elastic Cloud on Kubernetes
  - Elasticsearch
applies_to:
  - Elastic Cloud Hosted: Generally available
  - Elastic Cloud on Kubernetes: Generally available
  - Elastic Cloud Enterprise: Generally available
  - Self-managed Elastic deployments: Generally available
---

# Unbalanced shard counts
Shard counts across data nodes are skewed enough that some nodes carry far fewer shards than peers in the same tier. Uneven placement wastes capacity on light nodes and can overload heavier ones for indexing and search.
<note>
  For a complete list of insights, refer to [AutoOps insights](https://docs-v3-preview.elastic.dev/elastic/autoops-insights/tree/main/elasticsearch).
</note>


## Insight details


| Field     | Value                         |
|-----------|-------------------------------|
| Component | Elasticsearch                 |
| Severity  | Medium                        |
| Scope     | Node                          |
| Domains   | performance, shard-allocation |


## Customization settings

You can customize these settings to adjust when AutoOps detects this event and presents the insight. Refer to [AutoOps event settings](https://docs-v3-preview.elastic.dev/elastic/docs-content/tree/main/deploy-manage/monitor/autoops/ec-autoops-event-settings) for details.
The default customization settings are:

| Setting                                    | Type       | Default |
|--------------------------------------------|------------|---------|
| Unbalanced shard percent above the average | Percentage | `50`    |


## Example: What you might see in AutoOps

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.

### Some nodes have a significantly low number of shards


#### What was detected

Affected data tier: hot, warm.
Average number of shards per node: 12
Nodes with the lowest number of shards: - es-data-03: 8
Nodes with the highest number of shards: - es-data-01: 42

#### Recommendations

<note>
  AutoOps shows different recommendations depending on how their conditions match your deployment or cluster.
</note>

<dropdown title="Enable shard rebalance">
  **Condition**: Always shown for this insight.Reset `cluster.routing.rebalance.enable` so primary and replica shards can rebalance across nodes.
  ```json

  {
    "transient": {
      "cluster.routing.rebalance.enable": null
    },
    "persistent": {
      "cluster.routing.rebalance.enable": null
    }
  }
  ```

  <note>
    Requires the `manage cluster` privilege. Requires Elasticsearch 8.0.0 or later. This action changes cluster or index configuration.
  </note>
</dropdown>


#### Background and impact

Elasticsearch normally spreads shards across active data nodes in a tier through allocation (placing unassigned shards) and rebalancing (moving shards between nodes).
When those processes cannot even out placement, some nodes sit underused while others hold most of the work. Common blockers include turned off rebalancing, allocation filters or awareness settings, disk watermarks, and node attributes that limit where shards can live.
Uneven shard counts often show up as uneven CPU, heap, and disk pressure, which slows indexing and search on the busier nodes.

## Guide

[Cluster-level shard allocation and routing settings](https://docs-v3-preview.elastic.dev/elastic/elasticsearch/tree/main/reference/elasticsearch/configuration-reference/cluster-level-shard-allocation-routing-settings)