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About OKD Virtualization

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.

When you deploy OKD Virtualization with OpenShift Data Foundation, you must create a dedicated storage class for Windows virtual machine disks. See Optimizing ODF PersistentVolumes for Windows VMs for details.

You can use OKD Virtualization with OVN-Kubernetes 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 supported cluster version

OKD Virtualization 4.17 is supported for use on OKD 4 clusters. To use the latest z-stream release of OKD Virtualization, you must first upgrade to the latest version of OKD.

About volume and access modes for virtual machine disks

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

For best results, use the ReadWriteMany (RWX) access mode and the Block volume mode. This is important for the following reasons:

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

  • The Block volume mode performs significantly better than 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 with the following configurations:

  • Storage volume with ReadWriteOnce (RWO) access mode

  • Passthrough features such as GPUs

Set the evictionStrategy field to None for these virtual machines. The None strategy powers down VMs during node reboots.

Single-node OpenShift differences

You can install OKD Virtualization on single-node OpenShift.

However, you should be aware that Single-node OpenShift does not support the following features:

  • High availability

  • Pod disruption

  • Live migration

  • Virtual machines or templates that have an eviction strategy configured

Additional resources