Module 1: Architecture Tour & Storage Provisioning

Duration: 15 minutes
Type: Guided Tour

Learning Objectives

By the end of this module, you will:

  • Validate the pre-provisioned IBM Storage Fusion architecture

  • Understand the critical difference between RWO and RWX storage classes

  • Know which storage class to use for VMs vs. backups

Activity 1: Access the IBM Fusion UI

  1. Open the OpenShift Console: {openshift_console_url}

  2. Click the Application Picker (grid icon) in the top navigation bar

  3. Select IBM Storage Fusion from the list

  4. The Fusion dashboard opens at: {fusion_ui_url}

Verify that the Fusion UI shows:

  • Active storage cluster with healthy status

  • Data protection services available

  • Connected ODF backend

Activity 2: Inspect Storage Classes

From the OpenShift Console, navigate to Storage > StorageClasses. You will see several storage classes provided by ODF.

VM Block Storage (RWX)

oc get sc ocs-storagecluster-ceph-rbd-virtualization -o yaml

Look for these fields in the YAML output:

Provisioner

openshift-storage.rbd.csi.ceph.com

Reclaim Policy

Delete

description annotation

"Provides RWO and RWX Block volumes suitable for Virtual Machine disks"

mapOptions

krbd:rxbounce — enables multi-node block access for live migration

storageclass.kubevirt.io/is-default-virt-class

"true" — OpenShift Virtualization selects this class by default
Volume Mode and Access Modes are not fields on the StorageClass itself — they are set when creating a PVC. The description annotation tells you which modes this class supports.

RWX is the critical enabler for live migration. When a PVC is created with RWX access mode and Block volume mode, the disk can be mounted simultaneously on multiple nodes. This allows a VM to migrate from one node to another without detaching and reattaching its storage.

The mapOptions: krbd:rxbounce parameter is what makes this class different from the standard RBD class — it enables the kernel RBD client to handle concurrent multi-node access safely.

With a standard RWO volume, the VM would be permanently locked to a single node.

Standard Block Storage (RWO)

oc get sc ocs-storagecluster-ceph-rbd -o yaml

Compare the output to the virtualization class above. Notice that ocs-storagecluster-ceph-rbd is missing mapOptions and the kubevirt.io annotation. Its description annotation reads "Provides RWO Filesystem volumes, and RWO and RWX Block volumes" — it technically supports the same access modes, but without krbd:rxbounce it is not safe for VM live migration. Use this class for databases and stateful applications that don’t need multi-node access.

Object Storage (MCG)

oc get sc openshift-storage.noobaa.io -o yaml

openshift-storage.noobaa.io provides S3-compatible object storage via the Multicloud Object Gateway (NooBaa). In Module 3, this will be the backup target destination.

Filesystem Storage

oc get sc ocs-storagecluster-cephfs -o yaml

ocs-storagecluster-cephfs provides POSIX-compliant shared filesystem storage via CephFS. Suitable for applications needing shared file access (e.g., CMS, shared data directories).

Storage Class Quick Reference

Storage Class Type Access Use Case

ocs-storagecluster-ceph-rbd-virtualization

Block

RWO / RWX

Virtual Machines (live migration enabled via krbd:rxbounce)

ocs-storagecluster-ceph-rbd

Block

RWO / RWX

Databases, stateful apps (no VM live migration support)

ocs-storagecluster-cephfs

Filesystem

RWX

Shared file storage

openshift-storage.noobaa.io

Object (S3)

N/A

Backups, object storage

Verify the Cluster Health

oc get storagecluster -n openshift-storage

Expected output: Phase: Ready

oc get cephcluster -n openshift-storage -o jsonpath='{.items[0].status.ceph.health}' ; echo

Expected output: HEALTH_OK

References

Facilitator Notes: Keep this section moving quickly. Draw a sharp distinction between filesystem storage and raw block device exposure for VMs. Make sure attendees understand that the MCG (openshift-storage.noobaa.io) will be the target for backups in Module 3.