The hybrid cloud landscape continues to evolve, and IBM Cloud Red Hat OpenShift Kubernetes Service (ROKS) has taken a significant step forward with the recent availability of OpenShift Virtualization. This development marks a pivotal moment for enterprises looking to modernize their infrastructure while maintaining their existing virtual machine investments.

Red Hat OpenShift on IBM Cloud ROKS now supports the OpenShift Virtualization operator so now you can run your Virtual machine (VM) workloads on ROKS. See Installing the OpenShift Virtualization Operator on Red Hat OpenShift on IBM Cloud clusters

ROKS on VPC provides a managed Kubernetes platform with integrated Red Hat OpenShift tooling. VPC-based clusters offer enhanced network isolation, multi-zone high availability, scalable infrastructure, and secure workload environments. This makes VPC an ideal foundation for running OpenShift Virtualization (Virt), which enables VM workloads alongside containers.

This is the first blog in a series of four blogs where we cover the following from a VMware administrator's perspective:

• Storage (this blog)
• Networking (coming soon)
• Migration (coming soon)
• Advanced Networking (coming soon)

What is OpenShift Virtualization on ROKS?

OpenShift Virtualization is a Kubernetes-native virtualization platform that allows organizations to run both containerized applications and virtual machines on a single, unified platform. On IBM Cloud ROKS, this capability extends the power of Red Hat's fully managed OpenShift service to include comprehensive VM management alongside traditional container orchestration.

The integration brings together the enterprise-grade security and scale of IBM Cloud with Red Hat's proven container platform, creating an environment where traditional VM workloads can coexist seamlessly with cloud-native applications.

OpenShift Virtualization on IBM Cloud ROKS supports both new and existing VM workloads, providing features such as:

• Live migration of VMs across cluster nodes for maintenance and load balancing
• High availability configurations for mission-critical workloads
• Dynamic provisioning of storage resources
• Network integration with OpenShift's software-defined networking
• Backup and disaster recovery aligned with cloud-native practices

Storage

As a VMware administrator venturing into OpenShift Virtualization, understanding the storage architecture is crucial for successful VM deployments and migrating VMs from VMware to OpenShift Virtualization. This blog explores how storage operates in ROKS OpenShift Virtualization and describes the most important concepts to grasp.

Persistent Volumes

Persistent Volumes (PVs) are a key component of Kubernetes storage. A PV is a piece of storage in the cluster that has been provisioned by an administrator or dynamically provisioned using StorageClasses. PVs have a lifecycle independent of any individual Pod that uses the PV.

Persistent Volume Claims

Persistent Volume Claims (PVCs) are requests for storage. A PVC can request specific size and access modes (e.g., ReadWriteOnce, ReadWriteMany). When a PVC is created, ROKS finds a PV that matches the request and binds them together. The PVC can then be used by Pods as storage.

StorageClasses

StorageClasses provide a way to describe the 'classes' of storage offered by a ROKS cluster. Different classes might map to quality-of-service levels, backup policies, or arbitrary policies determined by the cluster administrators. Each StorageClass contains the fields provisioner, parameters, and reclaimPolicy, which are used when a PersistentVolume belonging to the class needs to be dynamically provisioned.

Container Storage Interface

The Container Storage Interface (CSI) is a standard for exposing arbitrary block and file storage systems to containerized workloads on Kubernetes. CSI allows storage systems to integrate with Kubernetes without the need to modify core Kubernetes code. CSI drivers are developed by third-party storage providers and are deployed as Kubernetes resources.ROKS uses the File CSI to interface with IBM Cloud VPC File storage and the Block CSI to integrate with IBM Cloud VPC Block storage.

RWX Support

ReadWriteMany (RWX) support allows multiple Pods to read and write to the same volume. This is useful for shared storage scenarios, such as shared file systems or clustered applications. OpenShift Virtualization can use RWX volumes for VM disks that need to be accessed by multiple VMs or Pods.

OpenShift Data Foundation

OpenShift Data Foundation (ODF) provides a unified storage platform that supports block, file, and object storage. ODF integrates seamlessly with OpenShift Virtualization, providing dynamic provisioning, high availability, and advanced data services such as snapshots and disaster recovery.

OpenShift Virtualization Storage Usage

OpenShift Virtualization uses the storage components of ROKS to manage VM disk storage, snapshots, and RWX support. The integration IBM Cloud storage options and with OpenShift Data Foundation (ODF) provides a robust and scalable storage solution for VM workloads.

VM Disk Storage - VM disk storage in OpenShift Virtualization is managed using Persistent Volumes (PVs) and Persistent Volume Claims (PVCs). Each VM disk is backed by a PVC, which ensures that the disk persists beyond the lifecycle of the VM. This allows VMs to be restarted or migrated without data loss.

Snapshots - Snapshots provide a point-in-time copy of a VM disk. OpenShift Virtualization leverages the snapshot capabilities of the underlying storage system to create and manage VM snapshots. These snapshots can be used for backup, restore, and cloning operations.

Storage Requirements for OpenShift Virtualization

OpenShift Virtualization requires persistent storage for:

• Virtual machine disks.
• Shared volumes.
• Snapshots and backups.

Storage Options in IBM Cloud ROKS on VPC

OpenShift Data Foundation (ODF)

Best suited for OpenShift Virtualization and ideal for production-grade VM workloads requiring resilience, flexibility, and advanced data services.

• Ceph-based software-defined storage.
• Supports Block, File, and Object storage.
• RWX Support.
• Native CSI snapshots.
• Built-in with replication and self-healing.
• Integrated remote mirroring and backup.
• Cluster-native, auto-scaling. Dynamically scales as additional nodes are added and rebalances data.
• Deep OpenShift integration via operators.

IBM Cloud Block Storage

General-purpose block storage suitable for basic VM disk storage in non-critical environments.

• iSCSI Block storage.
• ReadWriteOnce only.
• No native CSI snapshot support for VMs.
• Zone-specific.
• No integrated remote mirroring.
• Does not automatically scale with workload demands or cluster growth, requires administrative intervention.
• CSI driver available, but limited VM-specific features.

IBM Cloud File Storage

NFS-based file storage, useful for shared volumes, but lacks VM-specific features and resilience.

• NFS File storage.
• RWX Support.
• No native VM snapshot support.
• Limited high availability.
• No integrated remote mirroring.
• Does not automatically scale with workload demands or cluster growth, requires administrative intervention.
• CSI driver available.

Summary Table

Recommended Architecture for OpenShift Virtualization on VPC

For production-grade OpenShift Virtualization on IBM Cloud VPC consider the following:

• Primary Storage: OpenShift Data Foundation (ODF).
• Backup/Archive: IBM Cloud Object Storage (integrated with ODF).
• Optional: IBM Cloud File for RWX workloads not tied to VMs.

Once ODF is installed, the following storage classes are available:

Summary 

The availability of OpenShift Virtualization on IBM Cloud ROKS represents more than just a feature addition, it's a strategic enabler for digital transformation. Organizations can now:

• Accelerate modernization initiatives without forcing immediate application rewrites
• Standardize on Kubernetes as the universal infrastructure layer
• Leverage IBM Cloud's enterprise capabilities including security, compliance, and global availability
• Future-proof their infrastructure by building on cloud-native foundations

As enterprises continue to navigate the complexity of hybrid and multi-cloud environments, platforms that can bridge traditional and modern architectures become increasingly valuable. OpenShift Virtualization on IBM Cloud ROKS positions organizations to take advantage of both worlds, preserving investments in VM-based applications while building capabilities for cloud-native innovation.

For IT leaders evaluating their infrastructure strategy, the combination of IBM Cloud's enterprise-grade platform with Red Hat's unified approach to VMs and containers offers a compelling path forward. The key is not choosing between virtualization and containerization, but rather finding ways to leverage both effectively within a modern, scalable architecture.

The availability of OpenShift Virtualization on IBM Cloud ROKS makes this vision a reality, providing the tools and platform capabilities needed to support both current operations and future innovation initiatives.