OpenShift Virtualization Service limitations

Virtual Private Cloud 4.21 and later Bare metal worker nodes only RHCOS only

Review the limitations and restrictions for OpenShift Virtualization Service clusters on Red Hat OpenShift on IBM Cloud.

Infrastructure requirements

  • VPC infrastructure with bare metal worker nodes only (no Classic or VSI support)
  • Available only in the following regions: Dallas (us-south), Washington DC (us-east), Toronto (ca-tor), Montreal (ca-mon), and Frankfurt (eu-de)
  • Bare metal flavors with openshift-vs tag (with NVME storage if ODF is required)
  • OpenShift 4.21 or later
  • Red Hat CoreOS (RHCOS) only
  • OVN-Kubernetes CNI only (automatically configured, cannot use Calico)
  • MTU settings are pre-configured (OVN: 8900, Worker nodes: 9000) and must not be changed

Configuration restrictions

The following components and settings are pre-configured and cannot be disabled or modified:

Add-ons
  • The openshift-virtualization add-on is automatically enabled and cannot be disabled
  • Optional add-ons are chosen from a limited selection suitable for virtualization
Operators
  • OpenShift Virtualization Operator (installed and managed by the add-on)
  • NMState Operator (installed and managed by the add-on)
  • Node Maintenance Operator (installed and managed by the add-on)
  • Installation of these operators from Red Hat OperatorHub is blocked
Storage
  • OpenShift Data Foundation (ODF) is pre-configured using bare metal flavors with local NVME storage
  • VPC Block Storage is not deployed or used in Virtualization Service clusters
  • All storage is provided through ODF with local disks
Networking
  • MTU settings are fixed (OVN: 8900, Worker nodes: 9000)
  • Outbound traffic protection is disabled and cannot be enabled

Installation of OpenShift Virtualization, NMState, and Node Maintenance operators from Red Hat OperatorHub is blocked on Virtualization Service clusters. These operators are managed exclusively by the openshift-virtualization add-on.

Storage and networking

Storage
  • ODF uses local NVME storage; node failures might cause data unavailability
  • VM snapshots supported but limited by storage capacity
Networking
  • VM live migration supported within same zone only (cross-zone requires shutdown)
  • Kubernetes network policies supported with some limitations

Virtual machines

  • You must provide and manage the licenses for the operating systems and software you install in your VMs, including Windows
  • GPU passthrough and vGPU might have limited support
  • Nested virtualization not supported
  • Migration between different bare metal flavors might have limitations

Licensing and scaling

Licensing
OVE licensing only. Per instance-hour for a bare metal worker node. BYOL and Cloud Pak entitlements are not supported. The entitlement parameter cannot be specified when creating Virtualization Service clusters or worker pools.
Scaling
  • All worker pools must use supported bare metal flavors
  • Minimum 3 worker nodes recommended for production
Availability
Bare metal capacity might not be available in all zones. Check before creating:
ibmcloud ks flavors --zone <zone> --provider vpc-gen2 | grep metal

Operations

  • Worker node maintenance might require VM migration or downtime
  • Backup and restore limited to ODF and OpenShift Virtualization features

When to use standard OpenShift

Use a standard OpenShift cluster if you need VSI worker nodes, custom storage, full OCP licensing, RHEL support, Calico CNI, or greater add-on flexibility.

Next steps