:_mod-docs-content-type: ASSEMBLY
include::_attributes/common-attributes.adoc[]
[id="etcd-guidance-span"]
= Guidance for clusters that span data centers
:context: etcd-guidance-span

toc::[]

[role="_abstract"]
Evaluate considerations and metrics for {product-title} clusters that span data centers so you can design supported, resilient multisite deployments.

Red{nbsp}Hat strongly recommends a deployment model where {product-title} clusters are deployed within a data center, but also acknowledges that there can be scenarios where a provider can use a deployment model where a cluster can span across data centers. This guidance outlines considerations when exploring the use of cluster deployments that span many data centers and describes important metrics that affect the supportability of such deployments. The design of such deployments must adhere to these guidelines for the product to function optimally and to ensure the highest quality of support with the appropriate product support subscriptions.

[WARNING]
====
A cluster deployment that spans many data centers extends the cluster as a single failure domain across locations and must not be considered a replacement for a disaster recovery plan.
====

Clusters that span many data centers follow standard Red{nbsp}Hat {product-title} support guidance. Review the "Red{nbsp}Hat {product-title} Lifecycle" and "Red{nbsp}Hat Production Support Scope of Coverage" for more information.

Do not deploy an {product-title} cluster that spans many sites. If you need presence in many data centers or regions, deploy one cluster per region or site, and use tools such as {rh-rhacm-title} to manage those clusters and deployments.

Some {product-title} platforms support many data center deployments. Check the platform-specific product documentation and release notes for details. Other platforms can span data centers, depending on the quality of the network connectivity between nodes. For more information, see "Ensuring reliable etcd performance and scalability".

When you implement a cluster deployment that spans many data centers, implement the practices in "Red{nbsp}Hat High Availability, and Recommended Practices". An alternative to multisite deployments is to deploy one {product-title} cluster per site, managed by {rh-rhacm-title}.

// Deployment caveats for multisite clusters
include::modules/etcd-deployment-caveats-span.adoc[leveloffset=+1]

// Infrastructure as a Service (IaaS) or cloud provider considerations
include::modules/etcd-iaas-cloud-provider-considerations-span.adoc[leveloffset=+1]

[role="_additional-resources"]
.Additional resources

* link:https://access.redhat.com/articles/7010220[Understanding and Validating MTU setting with {product-title} 4.x (Red{nbsp}Hat Knowledgebase)]
* link:https://docs.redhat.com/en/documentation/red_hat_openshift_data_foundation/4.19/html-single/configuring_openshift_data_foundation_disaster_recovery_for_openshift_workloads/index[Configuring {rh-storage} Disaster Recovery for OpenShift Workloads]

// Site recommendations
include::modules/etcd-site-recommendations-span.adoc[leveloffset=+1]

// Requirements for etcd, networking, and storage
include::modules/etcd-requirements-etcd-hardware-span.adoc[leveloffset=+1]

[role="_additional-resources"]
.Additional resources

* xref:../etcd/etcd-performance.adoc#etcd-leader-election-log-replication_etcd-performance[Ensuring reliable etcd performance and scalability]
* link:https://access.redhat.com/articles/7010220[Understanding and Validating MTU setting with {product-title} 4.x (Red{nbsp}Hat Knowledgebase)]
* xref:../etcd/etcd-performance.adoc#etcd-peer-round-trip_etcd-performance[How etcd peer round trip time affects performance]
* xref:../etcd/etcd-performance.adoc#etcd-database-size_etcd-performance[Determining the size of the etcd database and understanding its effects]

// Workload placement considerations
include::modules/etcd-workload-placement-considerations-span.adoc[leveloffset=+1]

[role="_additional-resources"]
[id="additional-resources-etcd-span_{context}"]
== Additional resources

* link:https://access.redhat.com/support/policy/updates/openshift[Red{nbsp}Hat {product-title} Lifecycle]
* link:https://access.redhat.com/support/offerings/production/soc[Red{nbsp}Hat Production Support Scope of Coverage]
* xref:../etcd/etcd-performance.adoc#etcd-leader-election-log-replication_etcd-performance[Ensuring reliable etcd performance and scalability]
* link:https://access.redhat.com/articles/3221001[Red{nbsp}Hat {product-title} High Availability, and Recommended Practices (Red{nbsp}Hat Knowledgebase)]
