About OKD Virtualization

Learn about OKD Virtualization’s capabilities and support scope.

What you can do with OKD Virtualization

OKD Virtualization is an add-on to OKD that allows you to run and manage virtual machine workloads alongside container workloads.

OKD Virtualization adds new objects into your OKD cluster by using Kubernetes custom resources to enable virtualization tasks. These tasks include:

  • Creating and managing Linux and Windows virtual machines (VMs)

  • Running pod and VM workloads alongside each other in a cluster

  • Connecting to virtual machines through a variety of consoles and CLI tools

  • Importing and cloning existing virtual machines

  • Managing network interface controllers and storage disks attached to virtual machines

  • Live migrating virtual machines between nodes

An enhanced web console provides a graphical portal to manage these virtualized resources alongside the OKD cluster containers and infrastructure.

OKD Virtualization is designed and tested to work well with Red Hat OpenShift Data Foundation features.

You can use OKD Virtualization with the OVN-Kubernetes, OpenShift SDN, or one of the other certified network plugins listed in Certified OpenShift CNI Plug-ins.

You can check your OKD Virtualization cluster for compliance issues by installing the Compliance Operator and running a scan with the ocp4-moderate and ocp4-moderate-node profiles. The Compliance Operator uses OpenSCAP, a NIST-certified tool, to scan and enforce security policies.

OKD Virtualization integration with the Compliance Operator is a Technology Preview feature only. Technology Preview features are not supported with Red Hat production service level agreements (SLAs) and might not be functionally complete. Red Hat does not recommend using them in production. These features provide early access to upcoming product features, enabling customers to test functionality and provide feedback during the development process.

For more information about the support scope of Red Hat Technology Preview features, see Technology Preview Features Support Scope.

OKD Virtualization supported cluster version

OKD Virtualization 4.13 is supported for use on OKD 4.13 clusters. To use the latest z-stream release of OKD Virtualization, you must first upgrade to the latest version of OKD.

About storage volumes for virtual machine disks

If you use the storage API with known storage providers, volume and access modes are selected automatically. However, if you use a storage class that does not have a storage profile, you must select the volume and access mode.

For best results, use accessMode: ReadWriteMany and volumeMode: Block. This is important for the following reasons:

  • The ReadWriteMany (RWX) access mode is required for live migration.

  • The Block volume mode performs significantly better in comparison to the Filesystem volume mode. This is because the Filesystem volume mode uses more storage layers, including a file system layer and a disk image file. These layers are not necessary for VM disk storage.

    For example, if you use Red Hat OpenShift Data Foundation, Ceph RBD volumes are preferable to CephFS volumes.

You cannot live migrate virtual machines that use:

  • A storage volume with ReadWriteOnce (RWO) access mode

  • Passthrough features such as GPUs

Do not set the evictionStrategy field to LiveMigrate for these virtual machines.

Single-node OpenShift differences

You can install OKD Virtualization on a single-node cluster.

When provisioning a single-node OpenShift cluster with the assisted installer, preconfigured persistent storage is deployed automatically.

  • In OKD Virtualization 4.10 and 4.11, the HostPath Provisioner (HPP) is automatically installed.

  • In OKD Virtualization 4.12, the OpenShift Data Foundation Logical Volume Manager Operator is the provided out-of-the-box storage solution. You can also manually deploy using the HPP.

Single-node OpenShift does not support high availability. Be aware of the following differences in functionality from a multiple-node cluster:

  • Pod disruption budgets are not supported.

  • Live migration is not supported.

  • Due to differences in storage behavior, some virtual machine templates are incompatible with single-node OpenShift. To ensure compatibility, templates or virtual machines that use data volumes or storage profiles must not have the eviction strategy set.

Additional resources