Bug 1826292

Document URL: 
 - https://docs.openshift.com/container-platform/4.4/release_notes/ocp-4-4-release-notes.html
 - https://docs.openshift.com/container-platform/4.4/installing/installing_vsphere/installing-vsphere.html
 Maybe much more...

Section Number and Name: Using ReadWriteOnce volume for internal Image Registry

Describe the issue: 

Since OpenShift 4.4 it is possible to use a ReadWriteOnce volume for internal image registry storage.

Tested in vSphere with:

```
oc create -f - <<EOF
kind: PersistentVolumeClaim
apiVersion: v1
metadata:
  name: image-registry-pvc
  namespace: openshift-image-registry
spec:
  accessModes:
    - ReadWriteOnce
  resources:
    requests:
      storage: 100Gi
  storageClassName: thin
EOF

oc patch configs.imageregistry.operator.openshift.io/cluster \
    --type='json' \
    --patch='[
        {"op": "replace", "path": "/spec/managementState", "value": "Managed"},
        {"op": "replace", "path": "/spec/rolloutStrategy", "value": "Recreate"},
        {"op": "replace", "path": "/spec/replicas", "value": 1},
        {"op": "replace", "path": "/spec/storage", "value": {"pvc":{"claim": "image-registry-pvc" }}}
    ]'

```

By using a ReadWriteOnce volume you have to
    - Change the Rollout Strategy from rolling to recreate and
    - its only supported to have exactly one replica.

That means, during a cluster or image-registry upgrade, your internal registry has downtime between stopping the old pod and starting the new pod!

Suggestions for improvement: 

Add a chapter and support status information. 

Additional information: 
    - https://issues.redhat.com/browse/RFE-489
    - https://issues.redhat.com/browse/DEVEXP-523
    - https://bugzilla.redhat.com/show_bug.cgi?id=1798759