
:guide-id: introduction
:guide-parent: 
:guide-title: High availability overview
:guide-summary: Explore the different {project_name} high-availability architectures
:guide-priority: 999
:guide-tile-visible: true
:version: 26.4.0

include::../attributes.adoc[]

[[introduction]]
= High availability overview

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{project_name} can be deployed in a number of high-availability architectures, allowing system administrators to pick the deployment type most suitable
for their needs. Ease of deployment, cost and fault-tolerance guarantees are important considerations when determining the correct architecture
for your deployments.

ifeval::[{project_product} == true]

Any {project_name} deployment must be installed on a properly configured OpenShift cluster that has been configured per
the https://docs.redhat.com/en/documentation/openshift_container_platform/4.19/html/installation_overview/index[OpenShift installation instructions].
For any {project_name} installations on OpenShift clusters that span multiple sites (i.e. single cluster or multi-clusters across multiple availability zones)
the OpenShift cluster must adhere to the https://access.redhat.com/articles/3220991[Guidance for Red Hat OpenShift Container Platform Clusters].

Ultimately high availability architectures involve many components in addition to the software running and the responsibility
for availability of the service is with the customer. This guide has recommended practices for using the {project_name}
in such high availability architectures.

endif::[]

== Architectures

This document describes two high availability architectures in which to deploy {project_name}: Single-cluster deployments and multi-cluster deployments.

=== Single-cluster deployments

Deploy {project_name} in a single cluster, optionally across multiple availability-zones or data centers with the required
network latency and database configuration, using link:{links_high-availability_single-cluster-introduction_url}[{links_high-availability_single-cluster-introduction_name}].

Advantages::
* No external dependencies

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* Deployment in a single {kubernetes} cluster

endif::[]

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* Deployment in a single {kubernetes} cluster or a set of virtual machines with transparent networking

endif::[]

* Tolerate availability-zone failure or data center failure, if deployed to multiple availability zones or data centers

Disadvantages::
* {kubernetes} cluster is a single point of failure:
** Control-plane failures could impact all {project_name} pods

=== Multi-cluster deployments

Connect two {project_name} clusters deployed for example in different {kubernetes} clusters in two availability zones
or data centers with the required network latency and database configuration using link:{links_high-availability_multi-cluster-introduction_url}[{links_high-availability_multi-cluster-introduction_name}].

Advantages::
* Tolerate availability-zone failure
* Tolerate {kubernetes} cluster failure
* Bridge two networks that do not offer transparent networking
* Regulatory compliance when distinct deployments are required

Disadvantages::
* Complexity:
** External load-balancer required
** Separate {jdgserver_name} cluster required on each site
* Cost:
** Additional load-balancer required
** Additional compute is required for external {jdgserver_name} clusters
** Two {kubernetes} control-planes must be provisioned
* Not supported with three or more availability zones

=== Next Steps

To learn more about the different high-availability architectures and their supported configurations, please consult the individual {sections}.

ifeval::[{project_product} != true]
* link:{links_high-availability_single-cluster-introduction_url}[{links_high-availability_single-cluster-introduction_name}]
* link:{links_high-availability_multi-cluster-introduction_url}[{links_high-availability_multi-cluster-introduction_name}]
endif::[]


