Red Hat OpenShift

Self-managed Red Hat OpenShift sizing and subscription guide


This will help you understand the subscription model for self-managed Red Hat® OpenShift® offerings and provide easy-to-follow, step-by-step instructions for how to approximate the size of a Red Hat OpenShift environment. More accurate sizing information is available on request.


Red Hat OpenShift subscription offerings

Red Hat OpenShift is a consistent applications development and management platform across an open hybrid cloud environment, and supports on-premises virtual and physical infrastructure, private cloud, public cloud and edge deployments. There are two ways to operate and consume Red Hat OpenShift: self-managed Red HatOpenShift and fully managed Red Hat OpenShift cloud services.

Self-managed OpenShift allows the customer to install, operate and manage OpenShift environments with the maximum control, flexibility and customization of operating their own environment from the infrastructure up. Self-managed OpenShift is supported on-premises on physical servers, virtualization and private cloud; as well as in supported public clouds. The customer controls upgrades, manages the lower level infrastructure, and maintains SLA.

Fully managed OpenShift cloud services are managed and operated by Red Hat and its public cloud partners in major public clouds. A dedicated site reliability engineering (SRE) team manages and maintains the OpenShift core services and infrastructure, allowing a customer’s DevSecOps team to concentrate on developing and deploying new applications and modernizing existing ones.

All editions of Red Hat OpenShift offer a consistent user experience for developers and operations across every footprint, allowing customers to easily transfer their skills and their applications to the clouds where their applications run best.


Self-managed OpenShift software offerings

  • Red Hat OpenShift Kubernetes Engine (RHOKE):  A hybrid cloud, enterprise Kubernetes runtime engine, that provides core OpenShift functionality to deploy and run applications, that is installed and managed by customers in data center, public cloud or edge environments.

  • Red Hat OpenShift Container Platform (RHOCP): A hybrid cloud, enterprise Kubernetes platform to build, deploy and run applications, that is installed and managed by customers in data center, public cloud or edge environments.

  • Red Hat OpenShift Platform Plus (RHOPP): A single hybrid-cloud platform for allowing enterprises to build, deploy, run and manage intelligent applications securely at scale across multiple clusters and cloud footprints. Multiple layers of security, manageability and automation provide consistency throughout the software supply chain.

Fully managed OpenShift cloud service offerings



Red Hat OpenShift Kubernetes Engine

Subscription components

  1. Red Hat OpenShift Kubernetes Engine is the Kubernetes runtime engine and infrastructure, and does not include the developer capabilities and advanced features of OpenShift Container Platform. OpenShift Kubernetes Engine includes the OpenShift Kubernetes distribution, RHEL and RHEL CoreOS (described below) and integrated Kubernetes cluster services components which include the OpenShift installer, monitoring, log forwarding, SDN, ingress router, registry and more.  See About OpenShift Kubernetes Engine in the OpenShift documentation for details.

  2. Red Hat Enterprise Linux and Red Hat Enterprise Linux CoreOS: Each OpenShift subscription contains all the software needed for your worker nodes, control plan nodes, and supporting infrastructure nodes. This includes both the Red Hat Enterprise Linux CoreOS (RHEL CoreOS) and Red Hat Enterprise Linux (RHEL) software. RHEL CoreOS is required for the OpenShift control plane.  RHEL CoreOS is supported only for use as a component of OpenShift. OpenShift customers can also choose to use RHEL version 7 for their OpenShift worker nodes, as an alternative to RHEL CoreOS. RHEL version 7 must be installed separately by the customer on those worker nodes. The RHEL software is included in OpenShift subscriptions for this express purpose.



Red Hat OpenShift Container Platform

Subscription components

  1. Red Hat OpenShift Kubernetes Engine: Each OpenShift Container Platform subscription includes all of the components of OpenShift Kubernetes Engine (as described above) as well as additional layered services described below.

  2. Red Hat Software Collections: OpenShift lets you use the container images provided in Red Hat Software Collections. These images include popular languages and runtimes—such as PHP, Python, Perl, Node.js, and Ruby—as well as databases, such as MySQL, MariaDB, and Redis. This offering also includes an OpenJDK image for Java™ frameworks. For more information, read the Red Hat Software Collections technology brief

  3. Red Hat JBoss Web Server: OpenShift subscriptions include Red Hat JBoss® Web Server, an enterprise solution that combines the Apache web server with the Apache Tomcat servlet engine, supported by Red Hat. OpenShift includes an unlimited right to use JBoss Web Server. Learn more at

  4. Red Hat Single sign-on (SSO): Red Hat provides Web SSO and identity federation based on security assertion markup language (SAML) 2.0, OpenID Connect, and Open Authorization (OAuth) 2.0 specifications. This capability, included in OpenShift subscriptions, may only be deployed inside OpenShift environments. However, any application—whether deployed inside or outside of OpenShift—may use Red Hat’s SSO.

  5. Log Management:  Adds support for log aggregation and management via Elasticsearch and Kibana integrated with Fluentd for log collection.

  6. Red Hat CodeReady Workspaces: A collaborative Kubernetes-native development environment that delivers OpenShift workspaces and an in-browser integrated development environment (IDE).

  7. Red Hat build of Quarkus: A full-stack, Kubernetes-native Java framework made for Java virtual machines (JVMs) and native compilation, optimizing Java specifically for containers and enabling it to become an effective platform for serverless, cloud, and Kubernetes environments.

  8. Red Hat OpenShift Virtualization: Accelerate application delivery with a single platform that can manage VMs and containers with the same tools and teams. OpenShift Virtualization enables OpenShift to manage and consume both containers and VMs with Kubernetes, using KubeVirt.

  9. Red Hat OpenShift Console: Provides an optimized experience for both developers and administrators. The developer perspective grants visibility into application components, and the administrative perspective allows the user to drill down to the OpenShift and Kubernetes resources.

  10. Red Hat OpenShift Pipelines: Automate and control application delivery across on-premise and public cloud platforms with Kubernetes-native CI/CD pipelines based on Tekton.

  11. Red Hat OpenShift Serverless: Event-driven serverless containers and functions that let you deploy and run serverless containers. Powered by a rich ecosystem of event sources, you can manage serverless apps natively in OpenShift. Based on Knative, OpenShift Serverless allows you to run serverless applications anywhere OpenShift runs.

  12. Red Hat OpenShift Service Mesh: Red Hat OpenShift Service Mesh provides a uniform way to connect, manage, and observe microservice-based applications, including Istio to manage and secure traffic flow across services, Jaeger for distributed tracing, and Kiali to view configuration and monitor traffic.

  13. Red Hat Insights for OpenShift: Red Hat Insights for OpenShift is a set of hosted services on included with a Red Hat subscription that leverage 1) configuration and utilization data sent from customer deployments to, and 2) rule-based analytical models, to help customers 3) track and optimize spend, improve stability and performance.

  14. IBM Cloud Satellite: Red Hat OpenShift Container Platform customers, who choose to purchase and deploy the IBM Cloud Satellite solution, are allowed to leverage their OpenShift node subscription for the entitlement of the customer workload related ROKS clusters located within their datacenter.  Customers can call IBM or Red Hat for support, but ultimately the support experience will start with IBM Cloud Satellite support services.  This OpenShift subscription usage is only eligible to customers deploying IBM Cloud Satellite within their datacenter and not on public clouds.  Cores are counted the same way explained in this document for normal OpenShift usage.



Red Hat OpenShift Platform Plus

Subscription components

  1. Red Hat OpenShift Container Platform: Each OpenShift Platform Plus subscription includes all of the components of OpenShift Container Platform (listed above) as well as additional layered products listed below to provide multicluster and hybrid cloud management and security at scale.

  2. Red Hat Advanced Cluster Management for Kubernetes: Red Hat Advanced Cluster Management for Kubernetes offers end-to-end management visibility and control to manage your cluster and application life cycle, along with security and compliance of your entire Openshift domain across multiple datacenters and public clouds. 

  3. Red Hat Advanced Cluster Security for Kubernetes: Red Hat Advanced Cluster Security for Kubernetes is the industry’s first Kubernetes-native security platform that enables organizations to securely build, deploy, and run cloud-native applications anywhere. RHACS delivers lower operational cost, reduced operational risk, and greater developer productivity through a Kubernetes-native approach that supports built-in security across the entire software development lifecycle.

  4. Red Hat Quay: Red Hat Quay is a trusted, open source registry platform for efficiently managing containerized content across global data centers, focusing on cloud-native and DevSecOps development models and environments. With its tight integration into OpenShift and long track record of running one of the largest public registry SaaS in the world, Quay gives customers a reliable and scalable place to centrally manage all software artifacts running on their clusters.



Self-managed OpenShift environments

Self-managed OpenShift (RHOPP, RHOCP or RHOKE) can be used anywhere that 64-bit Red Hat Enterprise Linux is certified and supported.

OpenShift 4 supports three primary deployment methods
  • Platform specific installer-provisioned infrastructure (IPI) - full integration, with underlying infrastructure platforms listed below, to automate the cluster provisioning and installation process. The installer provisions all resources necessary for cluster installation and configures integration between the OpenShift cluster and the infrastructure provider.

  • Platform specific user-provisioned infrastructure (UPI) - depending on the infrastructure platform, a varying amount of integration between OpenShift and the underlying platform is available. The administrator provisions the resources necessary for cluster installation. Depending on the platform, the installer may configure infrastructure integration and/or the administrator may add integration post-deployment.

  • Platform agnostic UPI - this deployment type provides no integration with the underlying infrastructure. This offers the broadest range of compatibility, however the administrator is responsible for creating and managing cluster infrastructure resources.

For self-managed deployments, OpenShift can be installed on
  • Bare metal servers
  • Virtualized environments, including:
    • VMware vSphere
    • Red Hat Virtualization
    • Other certified virtualization platforms — Other platforms are supported via the Platform Agnostic UPI install method.
  • Private clouds
    • Red Hat OpenStack® Platform
  • Public Clouds
    • Amazon Web Services, Azure, Google Cloud Platform
    • Other certified public cloud platforms — Other platforms are supported via the Platform Agnostic UPI install method.


For more information about which platforms are supported, visit the official OpenShift Container Platform documentation page.

Registration for Red Hat Cloud Access is required to use your OpenShift subscriptions on certified public clouds. For more information, visit

For more information on platforms and clouds that Red Hat OpenShift has been tested and certified on, refer to OpenShift Container Platform Tested Integrations at


Subscription types

Red Hat OpenShift Platform Plus (RHOPP), Red Hat OpenShift Container Platform  (RHOCP) and Red Hat OpenShift Kubernetes Engine (RHOKE) subscriptions are available in 2 options each with two support levels:

  • Core-based (2 Cores or 4 vCPUs) - This is based on the aggregate number of physical cores or virtual cores (vCPUs) across all the OpenShift worker nodes running  across all OpenShift clusters. Available with Standard 8x5 or Premium 24x7 support SLA.

  • Bare metal socket pair (1-2 sockets with up to 64 cores) - This is for x86 bare metal physical servers (IBM Z and Power not supported) with no virtualization installed, primarily for limited use cases like OpenShift Virtualization and workloads like AI/ML that benefit from direct hardware access without a virtualization layer.. Available with Standard 8x5 or Premium 24x7 support SLA.

As with Red Hat Enterprise Linux:

  • OpenShift subscriptions(RHOPP, RHOCP or RHOKE) are stackable to cover larger hosts.

  • Core-based subscriptions can be distributed across to cover all OpenShift worker nodes across all OpenShift clusters. For example, 100 2-core Red Hat OpenShift Platform Plus  subscriptions will provide 200 cores (400 vCPUs) that can be used across any number of worker nodes, across all running OpenShift clusters.


Disaster recovery

Red Hat defines three types of disaster recovery (DR) environments—Hot, Warm, and Cold. Paid OpenShift subscriptions are needed for Hot DR only.

Hot DR systems are defined as fully functional and running concurrently to the production systems. They are ready to immediately receive traffic and take over in the event of a disaster within the primary environment.

Warm DR systems are defined as already stocked with hardware representing a reasonable facsimile of that found in the primary site, but containing no customer data. To restore service, the last backups from the off-site storage facility must be delivered and bare metal restoration completed, before the real work of recovery can begin.

Cold DR systems are defined as having the infrastructure in place, but not the full technology (hardware, software) needed to restore service. 

For both Warm DR and Cold DR, the Red Hat OpenShift subscriptions can be transferred from the primary environment to the DR environment when the disaster occurs to restore service and maintain compliance with Red Hat's subscription terms.


Migration and swing upgrades

OpenShift 4 provides in-place upgrades between minor versions. However, for customers who are upgrading from OpenShift 3 or need to perform a swing upgrade due to maintenance windows or other considerations, your OpenShift subscription will cover both the original and destination infrastructure of a one-way migration until such migration is complete. During the migration, Red Hat's subscription management tools will show your environment as being out-of-compliance based on the number of OpenShift subscriptions you have purchased.  Red Hat allows this for major version upgrades and will not require the purchase of additional subscriptions to get back into compliance during the migration.  Finally, OpenShift provides tooling to assist in these migrations, along with Red Hat consulting services if desired. See documentation on Migration Toolkit for Containers.


Cores vs vCPUs and hyperthreading

Making a determination about whether or not a particular system uses one or more cores is currently dependent on whether or not that system has hyperthreading available. Note that hyperthreading is only a feature of Intel CPUs; to determine whether a particular system supports hyperthreading, visit

For systems where hyperthreading is enabled and where one hyperthread equates to one visible system core, then a calculation of cores at a ratio of 2 cores = 4 vCPUs is used.

In other words, a 2-core subscription covers 4 vCPUs in a hyperthreaded system. A large VM might have 8 vCPUs, equating to 4 subscription cores. As subscriptions come in 2-core units, you would need two 2-core subscriptions to cover these 4 cores or 8 vCPUs.

Where hyperthreading is not enabled, and where each visible system core correlates directly to an underlying physical core, a calculation of 2 cores = 2 vCPUs is used.


Core Bands 

OpenShift subscriptions use a system of measure called CORE BANDS. That means subscriptions (entitlements to consume OpenShift) are applied and consumed at the OpenShift cluster level and apply to all OpenShift worker nodes on that cluster. If a customer has multiple OpenShift clusters, they would aggregate the sum of cores consumed by the OpenShift worker nodes across all clusters to determine how many subscriptions are needed. For example, if a customer has 100 2-core RHOCP subscriptions, a total of 200 cores (400 vCPUs) are available to be applied to the OpenShift worker nodes across all running OpenShift clusters.


Bare metal server considerations

A physical server can be entitled using either core-based (2 core/4 vCPU) or socket-based (1-2 socket) OpenShift subscriptions.  If core-based subscriptions are used, the customer simply stacks a sufficient number of them to cover the total number of physical cores in the server.

In addition to core-based subscriptions, Red Hat offers OpenShift socket-based subscriptions as well. For certain deployment types, this is a more economical option. The socket-based subscriptions are limited to entitling an x86 server with up to 2 sockets with a total of 64 cores across them. Today, the socket-based subscriptions are available for x86 servers only and not for the IBM Z or Power architectures.

To entitle a physical server, stack one or more subscriptions to cover either the total number of sockets or physical cores in it (whichever is greater).  For example, a server has 2 sockets and 48 cores. One subscription is needed because the server has 2 sockets and less than 64 cores.  While a server with 2 sockets and 96 cores would need two subscriptions. That's because two subscriptions are needed to cover the 96 cores since a single subscription covers a maximum of 64 cores.

Bare metal socket-pair subscriptions also come with infrastructure subscriptions for the control plane and infrastructure. Best practice would be for these to also be bare metal physical servers to take advantage of our infrastructure automation which works in homogenous clusters. You do have the option of using a separate virtualized server as the control plane (creating a “mixed” cluster), but if you do so you must use the more manual agnostic installer method, and will not be able to take advantage of the infrastructure automation that is possible with an all-bare metal cluster (i.e., all worker and infrastructure nodes bare metal). 

Finally, use of the bare metal socket-pair subscriptions does not change the limitation of the number of containers per node (currently 250-500). Each physical bare metal server is a single node, and cannot use virtualization to carve it into a larger number of smaller nodes (for this you would need to use the core-based subscriptions). This means that the bare metal socket-pair model is best suited for a smaller number of “fatter” workloads like OpenShift Virtualization (where each workload is running a full virtual machine) or AI/ML (where each workload consumes a large amount of CPU and GPU).


Alternative architectures (IBM Z, Power)

Red Hat OpenShift Container Platform and OpenShift Platform Plus can also run on IBM Z and IBM LinuxONE systems and on IBM Power Systems for customers using these platforms as the standard for building and deploying cloud-native applications and microservices. Only the core-based subscription model is supported for IBM Z and IBM Power.

For IBM Z customers, Red Hat OpenShift does not require the entire physical node to be entitled, but only the cores used by OpenShift.  IBM Z customers know this as “sub-capacity” entitlement. Customers using only a subset of the available cores (compute capacity) on their IBM Z environment for RHOCP only require subscriptions for the subset that is used for the compute nodes. This applies regardless of how CPU partitioning is achieved, whether by CPU-pooling, capping, separate LPARs, or other means. In short, one (1) Integrated Facility for Linux (IFL) requires one (1) OpenShift core-based subscription. 

Red Hat OpenShift Platform Plus components beyond OpenShift Container Platform are not supported on IBM Z and IBM LinuxONE systems or on IBM Power Systems at this time with the following exceptions: 

  • A standalone subscription of Red Hat Quay running on x86 architectures provides a global registry for multiple architectures, including IBM Z and IBM Power clusters. Red Hat Quay itself will not run on IBM Z or Power. 

  • A standalone subscription of Red Hat Advanced Cluster Management (RHACM) running on x86 architecture can manage IBM Z environments. RHACM itself cannot run on an IBM Z environment. 

Red Hat OpenShift Kubernetes Engine (RHOKE) is not supported on IBM Z and IBM LinuxONE systems, nor on IBM Power Systems.


Microsoft Windows Server containers support

Self-managed Red Hat OpenShift supports Windows containers. Support is limited to a supported subset of installation infrastructures and OpenShift features. Only Windows container worker nodes are supported; the control and infrastructure planes of the OpenShift environment must be running on x86 infrastructure. For this reason, Windows container support is sold as a standalone subscription priced by core.  

Red Hat OpenShift Platform Plus and Red Hat OpenShift Container Platform infrastructure can be used to deploy and manage Windows worker workers, but the subscriptions must be purchased separately.

Red Hat Advanced Cluster Management for Kubernetes (ACM) and Red Hat Advanced Cluster Security for Kubernetes (ACS) are not supported for managing Windows nodes, but Red Hat Quay running on x86 architectures can manage container images for Windows container worker nodes.


Red Hat OpenShift Platform Plus component support

The components of the RHOPP subscription have different levels of support for alternative (non-x86) architectures and for Windows. Here is an overview of that support:


For more details, see the compatibility matrices for Red Hat OpenShift Container Platform, Red Hat Advanced Cluster Management (version 2.2 latest at this writing), Red Hat Advanced Cluster Security, and Red Hat Quay.

Red Hat OpenShift Platform Plus includes additional software beyond the core OpenShift Container Platform to help the customer manage and secure their OpenShift environment at scale across multiple clusters and multiple clouds. RHOPP is available both in the core-based and bare metal socket-pair subscription models with the limitations listed above.

The additional software included with RHOPP is generally limited to managing the nodes entitled with RHOPP subscriptions. For example, the subscription for Red Hat Advanced Cluster Management (RHACM) included with RHOPP can be used to manage any RHOPP nodes and clusters. If a customer wishes, say, to also manage some Red Hat OpenShift Service on AWS (ROSA) clusters, they would need to purchase additional RHACM add-on licenses to cover those clusters. 

The additional software subscriptions are also not separable from the RHOPP subscription. For example, the customer cannot purchase 100 RHOPP subscriptions, and install 200 cores of Red Hat OpenShift Container Platform subscriptions, and separately use RHACM to manage 200 cores of ARO with the same subscription. The additional software can only be used to manage the same 200 cores on which the core RHOPP software is installed.

Specific rules for each layered product are:

  • Red Hat Advanced Cluster Management for Kubernetes: RHOPP subscription allows the customer to install as many RHACM central instances as needed to manage their environment, and covers the management of all nodes and clusters entitled with RHOPP. If the customer wants to manage nodes and clusters without RHOPP entitlements (for example, the customer also has self-managed RHOCP or RHOKE entitled clusters, clusters running in a fully managed OpenShift cloud, or third-party Kubernetes environments supported by RHACM), then the customer needs to purchase RHACM add-on subscriptions to cover those environments. They can choose to manage them centrally from the RHACM console installed on RHOPP, or from a separate central application if that meets their requirement. More information on RHACM licenses, RHACM supported environments, and RHACM best practices can be found on  

  • Red Hat Advanced Cluster Security for Kubernetes:  The RHOPP subscription allows the customer to install as many RHACS central applications as needed to manage their environment, and covers the management of all nodes and clusters entitled with RHOPP. If the customer wants to manage nodes and clusters without RHOPP entitlements (for example, the customer also has self-managed RHOCP or RHOKE entitled clusters, clusters running in a fully managed OpenShift cloud, or third-party Kubernetes environments supported by RHACS), then the customer needs to purchase RHACS add-on subscriptions to cover those environments. Red Hat’s suggested practice is to manage each environment with a separate RHACS central application. More information on RHACS supported environments can be found on

  • Red Hat Quay: The RHOPP subscription allows the customer to install Red Hat Quay on any cluster that has a RHOPP entitlement. The number of Quay deployments is not limited. This Quay registry then can serve any supported Kubernetes environment the customer wishes, including the RHOPP environment, other self-managed OpenShift clusters, Managed OpenShift services, and supported third-party Kubernetes.  If the customer wishes to install Quay in a non-RHOPP environment, they will need to purchase a separate Red Hat Quay subscription. Red Hat Quay is also available as a fully managed SaaS offering at



Example initial self-managed OpenShift deployment

The following example bill of materials provides an extremely flexible, scalable Red Hat OpenShift environment designed to run as virtual machines and support hundreds of application containers:

  • 16 x OpenShift Platform Plus, 2-Core Premium subscriptions, including:

    • Control plane nodes (3 VMs)

    • Additional infrastructure nodes (3 VMs)

    • Worker nodes (16 VMs sized at 2 cores or 4 vCPUs)

    • Multicluster management, advanced observability and policy compliance

    • Declarative security and active threat detection and response

    • Scalable global container registry

  • 16 x Red Hat OpenShift Data Foundation: Adds scalable block and file storage for applications inside OpenShift.  This is an optional add-on for customers running stateful applications that require storage.

Red Hat also offers many additional application services and runtimes that have their own subscription and consumption models.



Self-managed Red Hat OpenShift sizing 

To conduct a more thorough sizing exercise to determine how many self-managed OpenShift (RHOPP, RHOCP or RHOKE) or add-on subscriptions you need, use the following questions and examples.

A few basic OpenShift terms are used in these sizing exercises:

  • Pod: The smallest deployable Kubernetes unit in OpenShift. A Kubernetes pod instance could have a single container or multiple containers running as sidecars.

  • Application instance: An “application” may be a single pod instance or may be deployed across multiple pod instances that make up an application service.  For example a highly available Tomcat application service may consist of 2 (or more) Tomcat pods.

  • Worker node: Instances (VMs or bare metal hosts) of Red Hat Enterprise Linux or Red Hat Enterprise Linux CoreOS where end user application pods run. OpenShift environments can have many worker nodes.

  • Control Plane nodes: Instances (VMs or bare metal hosts) of Red Hat Enterprise Linux CoreOS that act as the Kubernetes orchestration/management layer for OpenShift. Control plane nodes are included in self-managed OpenShift  subscriptions. See the “OpenShift Control Plane and Infrastructure nodes” section for more details.

  • Infrastructure nodes: Instances (virtual or physical hosts) of Red Hat Enterprise Linux or Red Hat Enterprise Linux CoreOS that are running pods supporting OpenShift’s cluster infrastructure or running the HAProxy-based load balancer for ingress traffic. Infrastructure nodes are included in self-managed OpenShift  subscriptions. See the “OpenShift Control Plane and Infrastructure nodes” section for more details.

  • Cluster: An OpenShift Kubernetes cluster consisting of a control plane and one or more worker nodes.

In summary:

  • Applications are packaged in container images.

  • Containers are deployed as pods.

  • Pods run on Kubernetes worker nodes, which are managed by the Kubernetes control plane nodes.


OpenShift Control Plane and Infrastructure nodes

Each self-managed OpenShift subscription provides extra entitlements for OpenShift, Red Hat Enterprise Linux, and other OpenShift-related components. These extra entitlements are included for the purpose of running OpenShift control plane and infrastructure nodes.


Infrastructure nodes

The OpenShift installer deploys a highly available OpenShift control plane comprised of three control plane nodes, in addition to OpenShift worker nodes to run end user applications. By default, Kubernetes control plane components (i.e. API server, etcd, scheduler, etc.) and supporting cluster services (i.e. monitoring, registry, etc.) will be deployed on the OpenShift control plane nodes.  However, customers may decide to move some of these supporting cluster services to dedicated infrastructure nodes.  

To qualify as an infrastructure node and use the included entitlement, only components that are supporting the cluster, and not part of an end user application, must be running on those instances. Examples include:

  • OpenShift registry

  • OpenShift Ingress Router (local and global/multicluster ingress)

  • OpenShift monitoring

  • OpenShift log management

  • HAProxy-based load balancer for cluster ingress 

  • Red Hat Quay

  • Red Hat OpenShift Container Storage

  • Red Hat Advanced Cluster Management

  • Red Hat Advanced Cluster Security

In addition, customers are permitted to deploy and run node-level monitoring, node enablement or provider enablement agents, on control plane and infrastructure nodes.  These agents must be scoped only to the node level and not provide external-facing application services themselves, and that end users do not interact with them directly.  Customers are permitted to deploy and run node-level monitoring, node enablement, provider enablement, or other customer developed management tools on control plane and infrastructure nodes. Examples of these may include:

  • Custom and third-party monitoring agents

  • CNI/CSI providers and supporting / enabling Pods

  • Hardware or virtualization enablement agents

  • Operators supporting ISV services

  • Custom Operators as deployment controllers

  • Custom logging and monitoring service for local cluster

No other end user application instances or types may be run on an infrastructure node using the included entitlement. To run other infrastructure workloads as application instances on OpenShift, you must run those instances on regular application nodes. Verify infrastructure status qualifications with Red Hat.


Control Plane Nodes

OpenShift Kubenetes control plane nodes generally are not used as worker nodes and by default will not run application instances. However, you may choose to use a control plane node as a node for hosting end user applications. Whether a control plane node requires a full OpenShift  subscription depends on whether it runs supporting OpenShift cluster components only or end user applications. See the “Infrastructure nodes” section above. 

In a Compact 3-Node cluster, end user application workloads are run on the control plane nodes. There is no special pricing for this and you would count the cores on the three nodes; regardless of the role they play.



Sizing Process

OpenShift subscriptions do not limit application instances. You can run as many application instances in the OpenShift environment as the underlying hardware and infrastructure will support. Larger-capacity hardware can run many application instances on a small number of hosts, while smaller-capacity hardware will require many hosts to run many application instances. The primary factor in determining the size of an OpenShift environment is how many pods, or application instances, will be running at any given time.


Step 1: Determine standard VM or hardware cores and memory

You may have a standard VM size for application instances or, if you typically deploy on bare metal, a standard server configuration. The following questions will help you more accurately understand your VM and hardware needs. Remember that in most cases, 2 vCPUs is equivalent to 1 core.




Step 2: Calculate number of application instances needed

Next, determine how many application instances, or pods, you plan to deploy. When sizing the environment, any application component deployed on OpenShift—such as a database, front-end static server, or message broker instance—is considered an application instance.

This figure can simply be an approximation to help you calculate a gross estimate of your OpenShift environment size. CPU, memory oversubscription, quotas and limits, and other features can be used to further refine this estimate.



Step 3: Determine preferred maximum OpenShift node utilization

We recommend reserving some space in case of increased demand, especially if autoscaling is enabled for workloads. Your preferred utilization will vary, based on historical load for the applications that will run on OpenShift.




Step 4: Determine total memory footprint

Next, calculate the total memory footprint of the deployed applications. If you are considering a completely greenfield environment, memory use data may not be available, but you can use educated approximations—for example, 1GB of memory per Java application instance—to make an estimate.



Step 5: Calculate totals

Finally, determine the number of OpenShift subscriptions needed based on the data gathered in steps 1-4.

  • Effective per node memory capacity (GB) 

= Preferred maximum OpenShift node utilization (%) * standard VM or hardware memory

  • Total memory utilization 

= Application instances * average application memory footprint

  • Number of nodes required to cover utilization 

= Total memory utilization / standard VM or hardware memory

  • Total required cores 

= Number of nodes required to cover utilization * standard VM or hardware cores

  • Effective virtual cores 

= Total required cores / 2

  • Number of OpenShift Platform Plus subscriptions 

= Total cores / 2 OR

= Effective virtual cores / 2


Example calculation for virtualized environments

System sizing (from steps 1-6 above)

  • Standard number of VM cores = 4 (hyperthreading used, 2 effective virtual cores)

  • Standard VM memory = 64GB

  • Preferred maximum node utilization = 80%

  • Average application memory footprint = 2GB

  • Number of application instances = 1500


Subscription calculations

  • Effective node memory capacity 

= 80% preferred maximum node utilization * 64GB standard VM memory 

= 51GB

  • Total memory utilization 

= 1500 application instances * 2GB average application memory footprint 

= 3000GB

  • Nodes required to cover utilization 

= 3000GB total memory utilization / 51GB effective node memory capacity 

= 59 nodes

  • Total cores 

= 59 nodes required * 2 cores per node 

= 118 total cores

  • Total subscriptions 

= 118 total cores / 2 cores per subscription 

= 59 subscriptions


In this example, 59 2-core OpenShift Platform Plus 2-core subscriptions would be needed.

Note: OpenShift supports many scalability, overcommitment, idling, and resource quota/limiting features. The calculations above are guidelines, and you may be able to tune your actual environment for better resource use and/or smaller total environment size. OpenShift Platform Plus customers should also take into account the needs of the additional software applications (RHACM, RHACS and Quay) including storage and compute resources, even though they may not require additional worker subscriptions.