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Preparing for bare metal cluster installation

Prerequisites

Bare-metal cluster installation requirements for OKD Virtualization

If you plan to use OKD Virtualization on a bare-metal cluster, you must ensure that your cluster is configured correctly during installation. This is because OKD Virtualization requires certain settings that cannot be changed after a cluster is installed.

High availability requirements for OKD Virtualization

When discussing high availability (HA) features in the context of OKD Virtualization, this refers only to the replication model of the core cluster components, determined by the controlPlaneTopology and infrastructureTopology fields in the Infrastructure custom resource (CR). Setting these fields to HighlyAvailable offers component redundancy, which is distinct from general cluster-wide application HA. Setting these fields to SingleReplica disables component redundancy, and therefore disables OKD Virtualization HA features.

If you plan to use OKD Virtualization HA features, you must have three control plane nodes at the time of cluster installation. The controlPlaneTopology status in the Infrastructure CR for the cluster must be HighlyAvailable.

You can install OKD Virtualization on a single-node cluster, but single-node OpenShift does not support HA features.

Live migration requirements for OKD Virtualization

  • If you plan to use live migration, you must have multiple worker nodes. The infrastructureTopology status in the Infrastructure CR for the cluster must be HighlyAvailable, and a minimum of three worker nodes is recommended.

    You can install OKD Virtualization on a single-node cluster, but single-node OpenShift does not support live migration.

  • Live migration requires shared storage. Storage for OKD Virtualization must support and use the ReadWriteMany (RWX) access mode.

SR-IOV requirements for OKD Virtualization

If you plan to use Single Root I/O Virtualization (SR-IOV), ensure that your network interface controllers (NICs) are supported by OKD.

Additional resources

NIC partitioning for SR-IOV devices

OKD can be deployed on a server with a dual port network interface card (NIC). You can partition a single, high-speed dual port NIC into multiple virtual functions (VFs) and enable SR-IOV.

This feature supports the use of bonds for high availability with the Link Aggregation Control Protocol (LACP).

Only one LACP can be declared by physical NIC.

An OKD cluster can be deployed on a bond interface with 2 VFs on 2 physical functions (PFs) using the following methods:

  • Agent-based installer

    The minimum required version of nmstate is:

    • 1.4.2-4 for RHEL 8 versions

    • 2.2.7 for RHEL 9 versions

  • Installer-provisioned infrastructure installation

  • User-provisioned infrastructure installation

Additional resources

Choosing a method to install OKD on bare metal

The OKD installation program offers four methods for deploying a cluster:

  • Interactive: You can deploy a cluster with the web-based Assisted Installer. This is the recommended approach for clusters with networks connected to the internet. The Assisted Installer is the easiest way to install OKD, it provides smart defaults, and it performs pre-flight validations before installing the cluster. It also provides a RESTful API for automation and advanced configuration scenarios.

  • Local Agent-based: You can deploy a cluster locally with the agent-based installer for air-gapped or restricted networks. It provides many of the benefits of the Assisted Installer, but you must download and configure the agent-based installer first. Configuration is done with a commandline interface. This approach is ideal for air-gapped or restricted networks.

  • Automated: You can deploy a cluster on installer-provisioned infrastructure and the cluster it maintains. The installer uses each cluster host’s baseboard management controller (BMC) for provisioning. You can deploy clusters with both connected or air-gapped or restricted networks.

  • Full control: You can deploy a cluster on infrastructure that you prepare and maintain, which provides maximum customizability. You can deploy clusters with both connected or air-gapped or restricted networks.

The clusters have the following characteristics:

  • Highly available infrastructure with no single points of failure is available by default.

  • Administrators maintain control over what updates are applied and when.

See Installation process for more information about installer-provisioned and user-provisioned installation processes.

Installing a cluster on installer-provisioned infrastructure

You can install a cluster on bare metal infrastructure that is provisioned by the OKD installation program, by using the following method:

Installing an installer-provisioned cluster on bare metal

You can install OKD on bare metal by using installer provisioning.

Installing a cluster on user-provisioned infrastructure

You can install a cluster on bare metal infrastructure that you provision, by using one of the following methods:

Installing a user-provisioned cluster on bare metal

You can install OKD on bare metal infrastructure that you provision. For a cluster that contains user-provisioned infrastructure, you must deploy all of the required machines.

Installing a user-provisioned bare metal cluster with network customizations

You can install a bare metal cluster on user-provisioned infrastructure with network-customizations. By customizing your network configuration, your cluster can coexist with existing IP address allocations in your environment and integrate with existing MTU and VXLAN configurations. Most of the network customizations must be applied at the installation stage.

Installing a user-provisioned bare metal cluster on a restricted network

You can install a user-provisioned bare metal cluster on a restricted or disconnected network by using a mirror registry. You can also use this installation method to ensure that your clusters only use container images that satisfy your organizational controls on external content.