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Volume Provisioning

Overview

Volume provisioning involves making a PersistentVolumeClaim using default directpv-min-io storage class or a custom storage class having a directpv-min-io provisioner. The storage classes come with volume binding mode WaitForFirstConsumer. This mode delays volume binding and provisioning of a PersistentVolume until a Pod using the PersistentVolumeClaim is created.

DirectPV selects or provisions PersistentVolumes that match the topology specified by the Pod’s scheduling constraints. These include, but are not limited to, resource requirements, node selectors, pod affinity and anti-affinity, and taints and tolerations. Pods consuming volumes are scheduled to nodes where volumes were scheduled. This ensures high performance data access to the pod.

A DirectPV volume in Ready state indicates that the volume is ready for binding to the pod. After binding, Bound state is set to the volume.

Making Persistent volume claim

A PersistentVolume claim must be defined with specific parameters in a PersistentVolumeClaim specification.

These parameters are:

Parameter Value
volumeMode Filesystem
storageClassName directpv-min-io or any storage class name having directpv-min-io provisioner
accessModes [ "ReadWriteOnce" ]

Below is an example claiming 8MiB storage from directpv-min-io storage class for sleep-pvc PVC:

apiVersion: v1
kind: PersistentVolumeClaim
metadata:
  name: sleep-pvc
spec:
  volumeMode: Filesystem
  storageClassName: directpv-min-io
  accessModes: [ "ReadWriteOnce" ]
  resources:
    requests:
      storage: 8Mi

For WaitForFirstConsumer volume binding mode, a pod consuming sleep-pvc must be defined. Below is an example which uses sleep-volume mounted on /mnt:

apiVersion: v1
kind: Pod
metadata:
  name: sleep-pod
spec:
  volumes:
    - name: sleep-volume
      persistentVolumeClaim:
        claimName: sleep-pvc
  containers:
    - name: sleep-container
      image: example.org/test/sleep:v0.0.1
      volumeMounts:
        - mountPath: "/mnt"
          name: sleep-volume

Making Persistent volume claim in StatefulSet

PV claim must be defined with specific parameters in volumeClaimTemplates specification.

These parameters are:

Parameter Value
storageClassName directpv-min-io or any storage class name having directpv-min-io provisioner
accessModes [ "ReadWriteOnce" ]

Below is an example claiming two 16MiB storage from directpv-min-io storage class for minio-data-1 and minio-data-2 PVC to two minio pods:

kind: Service
apiVersion: v1
metadata:
  name: minio
  labels:
    app: minio
spec:
  selector:
    app: minio
  ports:
    - name: minio
      port: 9000

---

apiVersion: apps/v1
kind: StatefulSet
metadata:
  name: minio
  labels:
    app: minio
spec:
  serviceName: "minio"
  replicas: 2
  selector:
    matchLabels:
      app: minio
  template:
    metadata:
      labels:
        app: minio
        directpv.min.io/organization: minio
        directpv.min.io/app: minio-example
        directpv.min.io/tenant: tenant-1
    spec:
      containers:
      - name: minio
        image: minio/minio
        env:
        - name: MINIO_ACCESS_KEY
          value: minio
        - name: MINIO_SECRET_KEY
          value: minio123
        volumeMounts:
        - name: minio-data-1
          mountPath: /data1
        - name: minio-data-2
          mountPath: /data2
        args:
        - "server"
        - "http://minio-{0...1}.minio.default.svc.cluster.local:9000/data{1...2}"
  volumeClaimTemplates:
  - metadata:
      name: minio-data-1
    spec:
      storageClassName: directpv-min-io
      accessModes: [ "ReadWriteOnce" ]
      resources:
        requests:
          storage: 16Mi
  - metadata:
      name: minio-data-2
    spec:
      storageClassName: directpv-min-io
      accessModes: [ "ReadWriteOnce" ]
      resources:
        requests:
          storage: 16Mi

Further reading