StorageClasses

StorageClasses in Kubernetes are used to link PVCs with a backend storage provisioner - for instance, Ondat. A StorageClass defines parameters to pass to the provisioner, which in the case of Ondat can be translated into behaviour applied to the Volumes. Many StorageClasses can be provisioned to apply different feature labels to the Ondat Volumes.

By default the Ondat Cluster Operator installs the storageos StorageClass at bootstrap of Ondat. You can define its name in the Ondat Cluster Resource.

apiVersion: storage.k8s.io/v1
kind: StorageClass
allowVolumeExpansion: true
provisioner: csi.storageos.com
reclaimPolicy: Delete
volumeBindingMode: Immediate
parameters:
  csi.storage.k8s.io/fstype: ext4
  csi.storage.k8s.io/secret-name: storageos-api
  csi.storage.k8s.io/secret-namespace: storageos

StorageClasses can be created to define default labels for Ondat volumes, but also to map to any semantic aggregation of volumes that suits your use case, whether there are different roles (dev, staging, prod), or a StorageClass maps to a team or customer using the cluster.

Examples

You can find the basic examples in the Ondat use-cases repository, in the 00-basic/v2.5.storageclass-and-later directory.

git clone https://github.com/storageos/use-cases.git storageos-usecases
cd storageos-usecases/00-basic/v2.5.storageclass-and-later

Replicated Storage Class

StorageClass definition in v2-storageclass-replicated.yaml.

apiVersion: storage.k8s.io/v1
kind: StorageClass
metadata:
  name: storageos-rep
provisioner: csi.storageos.com
allowVolumeExpansion: true
parameters:
  csi.storage.k8s.io/fstype: ext4
  storageos.com/replicas: "1"
  csi.storage.k8s.io/secret-name: storageos-api
  csi.storage.k8s.io/secret-namespace: storageos

That StorageClass can be used by a PVC:

apiVersion: v1
kind: PersistentVolumeClaim
metadata:
  name: my-vol-1
spec:
  storageClassName: "ondat-replicated" # Ondat StorageClass
  accessModes:
    - ReadWriteOnce
  resources:
    requests:
      storage: 5Gi

The above StorageClass has the storageos.com/replicas label set. This label tells Ondat to create a volume with a replica. Adding Ondat feature labels to the StorageClass ensures all volumes created with the StorageClass have the same labels.

You can also choose to add the label in the PVC definition rather than the StorageClass. The PVC definition takes precedence over the StorageClass.

Topology Aware Storage Class

StorageClass that enables Topology Aware Placement and replication with soft mode:

apiVersion: storage.k8s.io/v1
kind: StorageClass
metadata:
  name: storageos-rep-enc-tap
provisioner: csi.storageos.com
allowVolumeExpansion: true
parameters:
  csi.storage.k8s.io/fstype: ext4
  storageos.com/replicas: "2"
  storageos.com/failure-mode: "soft"
  storageos.com/topology-aware: "true"
  csi.storage.k8s.io/secret-name: storageos-api
  csi.storage.k8s.io/secret-namespace: storageos

Encrypted volumes Storage Class

StorageClass that enables encryption and replication for volumes.

apiVersion: storage.k8s.io/v1
kind: StorageClass
metadata:
  name: storageos-rep-enc
provisioner: csi.storageos.com
allowVolumeExpansion: true
parameters:
  csi.storage.k8s.io/fstype: ext4
  storageos.com/replicas: "1"
  storageos.com/encryption: "true"
  csi.storage.k8s.io/secret-name: storageos-api
  csi.storage.k8s.io/secret-namespace: storageos