> For the complete documentation index, see [llms.txt](https://docs.datasentinel.io/manual/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://docs.datasentinel.io/manual/guides/readme/monitor-high-availability-clusters.md).

# Monitor High-Availability Clusters

<div data-with-frame="true"><figure><img src="/files/qiwnfcaqdoZ1PEsuxBhT" alt="Monitor High-Availability Clusters"><figcaption></figcaption></figure></div>

This guide explains how Datasentinel detects and manages HA clusters, how instances are grouped, and how to analyze workload and activity in highly available PostgreSQL environments.

## HA Cluster Detection

Datasentinel automatically detects the role of each PostgreSQL instance, identifying primary instances and read-only replicas based on runtime characteristics.

{% hint style="info" %}
If a failover occurs, Datasentinel updates instance roles automatically to reflect the new cluster topology.
{% endhint %}

## Using Tags with HA Clusters

[**Tags**](/manual/guides/readme/organize-content-using-tags.md) can be applied to PostgreSQL instances that belong to an HA cluster.

When instances share the same tag (for example, `ha_cluster=sales-app`), you can:

* Analyze the consolidated workload of the cluster
* Apply[ **role-based access control (RBAC)**](/manual/guides/readme/manage-users-and-role-based-access.md) at the cluster level
* [**Filter dashboards**](/manual/guides/readme/organize-content-using-tags.md) and reports by cluster or application

Tags combined with HA awareness provide powerful grouping and access-control capabilities.

## Consolidated Cluster View

Datasentinel provides a **cluster-level view** that aggregates activity across all instances in the HA cluster.

This allows you to:

* Analyze total workload across the cluster
* Compare activity between primary and replicas
* Identify load distribution and imbalance

Cluster-level analysis removes the need to inspect each instance individually.

<div data-with-frame="true"><figure><img src="/files/JfSiEkURRCrlPmjL5YAR" alt=""><figcaption></figcaption></figure></div>

## Workload Analysis Across HA Clusters

Using Datasentinel dashboards and analysis modules, you can:

* View [**Top Queries**](/manual/features/key-features/top-queries.md) across the entire cluster
* Analyze [**Session Activity**](/manual/features/key-features/session-history.md) on primary and replicas
* Identify queries executed on replicas only
* Detect replication-aware workload patterns

This is particularly useful for understanding how applications leverage read replicas.

<div data-with-frame="true"><figure><img src="/files/c6wawDtqpQIZoiH0XL01" alt=""><figcaption></figcaption></figure></div>

## Viewing Replication Statistics

Datasentinel collects and logs replication statistics for PostgreSQL read replicas, providing clear visibility into replication health.

For each replica, Datasentinel allows you to:

* View the **WAL delta size**, representing the amount of data remaining to be replicated
* Monitor **replication delay**, indicating how far replicas lag behind the primary instance

<div data-with-frame="true"><figure><img src="/files/Ycx7XmNJBJz32KgvF4tc" alt=""><figcaption></figcaption></figure></div>

## Common Use Cases

Typical HA cluster monitoring scenarios include:

* Analyzing total workload across primary and replicas
* Verifying that read traffic is correctly routed to replicas
* Comparing query patterns between instances
* Monitoring cluster behavior during failover events

## Best Practices

* Use consistent tags across all instances in an HA cluster
* Combine cluster-level analysis with instance-level dashboards
* Review workload distribution regularly
* Use tags to control access to entire clusters via RBAC

{% hint style="info" %}
Datasentinel is compatible with read replicas from managed PostgreSQL services offered by major public cloud providers, including Amazon RDS, Microsoft Azure, and Google Cloud.
{% endhint %}

## Where to go next

<table data-view="cards"><thead><tr><th></th><th></th><th data-hidden data-card-target data-type="content-ref"></th></tr></thead><tbody><tr><td><h4><i class="fa-tag" style="color:$primary;">:tag:</i></h4></td><td><strong>Organize Content using Tags</strong>: the shared cluster tag is what unlocks consolidated HA analysis.</td><td><a href="/pages/jdy0zIUnjZHb9XwBGH0Y">/pages/jdy0zIUnjZHb9XwBGH0Y</a></td></tr><tr><td><h4><i class="fa-users" style="color:$primary;">:users:</i></h4></td><td><strong>Manage Users and Role-Based Access</strong>: grant access to an entire cluster (primary plus replicas) through a single role.</td><td><a href="/pages/M5MUBWa2Y2eRROXypHwm">/pages/M5MUBWa2Y2eRROXypHwm</a></td></tr><tr><td><h4><i class="fa-cloud" style="color:$primary;">:cloud:</i></h4></td><td><strong>Monitor Cloud-Managed Instances</strong>: apply the same HA recipe to RDS, Azure, and Cloud SQL replica deployments.</td><td><a href="/pages/aGpRhzYSyd7klXa01uYC">/pages/aGpRhzYSyd7klXa01uYC</a></td></tr><tr><td><h4><i class="fa-rocket" style="color:$primary;">:rocket:</i></h4></td><td><strong>Onboard Your First PostgreSQL Cluster</strong>: get each individual instance monitored before grouping them into an HA cluster.</td><td><a href="/pages/A9sFriZivMT20vNkYp0w">/pages/A9sFriZivMT20vNkYp0w</a></td></tr></tbody></table>

## Conclusion

Datasentinel provides clear visibility into high-availability PostgreSQL environments by automatically detecting primary and replica roles and enabling consolidated activity analysis across instances.


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