// Module included in the following assemblies:
//
// * scalability_and_performance/telco_ran_du_ref_design_specs/telco-ran-du-rds.adoc

:_mod-docs-content-type: REFERENCE
[id="telco-ran-red-hat-advanced-cluster-management-rhacm_{context}"]
= Red Hat Advanced Cluster Management

[role="_abstract"]
{rh-rhacm} provides Multi Cluster Engine (MCE) installation and ongoing lifecycle management functionality for deployed clusters.

New in this release::
* No reference design updates in this release

Description::
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{rh-rhacm} provides Multi Cluster Engine (MCE) installation and ongoing lifecycle management functionality for deployed clusters.
You manage cluster configuration and upgrades declaratively by applying `Policy` custom resources (CRs) to clusters during maintenance windows.

{rh-rhacm} provides the following functionality:

* Zero touch provisioning (ZTP) of clusters using the MCE component in {rh-rhacm}.
* Configuration, upgrades, and cluster status through the {rh-rhacm} policy controller.
* During managed cluster installation, {rh-rhacm} can apply labels to individual nodes as configured through the `ClusterInstance` CR.

The recommended method for {sno} cluster installation is the image-based installation approach, available in MCE, using the `ClusterInstance` CR for cluster definition.

Image-based upgrade is the recommended method for {sno} cluster upgrade.
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Limits and requirements::
* A single hub cluster supports up to 3500 deployed {sno} clusters with 5 `Policy` CRs bound to each cluster.

Engineering considerations::
* Use {rh-rhacm} policy hub-side templating to better scale cluster configuration.
You can significantly reduce the number of policies by using a single group policy or small number of general group policies where the group and per-cluster values are substituted into templates.
* Cluster specific configuration: managed clusters typically have some number of configuration values that are specific to the individual cluster.
These configurations should be managed using {rh-rhacm} policy hub-side templating with values pulled from `ConfigMap` CRs based on the cluster name.
* To save CPU resources on managed clusters, policies that apply static configurations should be unbound from managed clusters after {ztp} installation of the cluster.
