When you run virtual machines (VMs) on Red Hat OpenShift Virtualization, storage becomes a key factor in how well your workloads perform. Unlike containers, which are often designed to be stateless, virtual machines need disks and persistent storage to ensure that data is not lost when a VM restarts.
Why Storage is Important for VMs
Virtual machines in OpenShift need storage that is:
Persistent – so data survives reboots and crashes.
Flexible – so you can attach multiple disks depending on workload needs.
Scalable – to grow with your applications.
High-performing – for speed and reliability in production environments.
How Storage Works in OpenShift Virtualization
OpenShift uses Kubernetes storage concepts to manage VM disks. Here are the main options:
Persistent Volumes (PVs) and Persistent Volume Claims (PVCs):
Think of this as “cloud storage requests.” Developers request storage (PVCs), and administrators provide the actual backend storage (PVs).
Storage Classes:
These act like templates for different kinds of storage—fast SSDs, regular HDDs, or cloud storage options.
DataVolumes:
This feature is specific to OpenShift Virtualization. It not only creates the disk but also lets you import an operating system image (like CentOS, RHEL, or Ubuntu) directly into the disk, so your VM can boot from it.
Container Storage Interface (CSI):
This is a standard way for OpenShift to connect with a wide variety of external storage providers. It makes storage provisioning, expansion, and snapshotting much simpler.
Typical Workflow for VM Storage
Here’s what storage management usually looks like when setting up VMs:
Step 1: Define your storage class (for example, fast SSD vs. general-purpose storage).
Step 2: Request a disk using that class.
Step 3: Attach the disk to your virtual machine so the VM can use it.
Step 4: (Optional) Import an OS image into the disk so the VM boots with a preconfigured system.
Best Practices
Choose the right storage type for the workload—don’t use the same disk type for a database and a dev/test VM.
Use snapshots and backups for critical workloads.
Monitor disk performance to avoid slowdowns.
For production, use highly available storage solutions like Ceph to reduce downtime risks.
Conclusion
By using Kubernetes-based storage concepts, OpenShift makes it straightforward to manage VM disks. Features like Persistent Volumes, Storage Classes, and DataVolumes provide the flexibility to configure storage for everything from small test workloads to large production clusters.
With the right storage strategy, you can ensure your virtual machines run smoothly and reliably in OpenShift.
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