// Module included in the following assemblies:
//
// * scalability_and_performance/telco_core_ref_design_specs/telco-core-rds.adoc

:_mod-docs-content-type: REFERENCE
[id="telco-hub-cluster-topology_{context}"]
= Hub cluster topology

[role="_abstract"]
In production environments, the {product-title} hub cluster must be highly available to maintain high availability of the management functions.

Limits and requirements::
Use a highly available cluster topology for the hub cluster, for example:
* Compact (3 nodes combined control plane and compute nodes)
* Standard (3 control plane nodes + N compute nodes)

Engineering considerations::
* In non-production environments, a {sno} cluster can be used for limited hub cluster functionality.
* Certain capabilities, for example {rh-storage-first}, are not supported on {sno}.
In this configuration, some hub cluster features might not be available.
* The number of optional compute nodes can vary depending on the scale of the specific use case.
* Compute nodes can be added later as required.
* Consult the 4.21 release notes regarding the decrease in the default maximum open files soft limit for containers in this release.
