Let's perform the following steps to create a storage class for Ceph storage.:

1. Create CephBlockPool:

$ cat <<EOF | kubectl apply -f -
apiVersion: ceph.rook.io/v1
kind: CephBlockPool
metadata:
  name: replicapool
  namespace: rook-ceph
spec:
  failureDomain: host
  replicated:
    size: 3
EOF

2. Create a Rook Ceph block storage class:

$ cat <<EOF | kubectl apply -f -
apiVersion: storage.k8s.io/v1
kind: StorageClass
metadata:
   name: rook-ceph-block
provisioner: rook-ceph.rbd.csi.ceph.com
parameters:
    clusterID: rook-ceph
    pool: replicapool
    imageFormat: "2"
    imageFeatures: layering
    csi.storage.k8s.io/provisioner-secret-name: rook-ceph-csi
    csi.storage.k8s.io/provisioner-secret-namespace: rook-ceph
    csi.storage.k8s.io/node-stage-secret-name: rook-ceph-csi
    csi.storage.k8s.io/node-stage-secret-namespace: rook-ceph
    csi.storage.k8s.io/fstype: xfs
reclaimPolicy: Delete
EOF

3. Confirm that the storage class has been created:

$ kubectl get sc
NAME              PROVISIONER                AGE
default (default) kubernetes.io/azure-disk   6h27m
rook-ceph-block   rook-ceph.rbd.csi.ceph.com 3s

As you can see from the preceding provisioner name, rook-ceph.rbd.csi.ceph.com, Rook also uses CSI to interact with Kubernetes APIs. This driver is optimized for RWO pod access where only one pod may access the storage.