PersistentVolumeClaim

Learn storage requests with a PVC.

PersistentVolumeClaim

A PersistentVolumeClaim (PVC) is an application's storage request: "5 GiB, writable by a single node". Kubernetes finds a PV matching the request and binds it (Bound) or creates a new one with a StorageClass. The application developer doesn't need to know infrastructure details (which disk, which cloud):

apiVersion: v1
kind: PersistentVolumeClaim
metadata:
  name: api-veri
spec:
  accessModes:
    - ReadWriteOnce
  storageClassName: standard
  resources:
    requests:
      storage: 5Gi

States

A PVC's state is Pending (no suitable PV, or waiting to be created) or Bound. The reason a PVC stays Pending is seen in the describe events:

$ kubectl get pvc
NAME       STATUS    VOLUME      CAPACITY   ACCESS MODES   STORAGECLASS
api-veri   Bound     pvc-9c1d…   5Gi        RWO            standard
eski       Pending                                         hizli-ssd
$ kubectl describe pvc eski | tail -2
  Warning  ProvisioningFailed  storageclass.storage.k8s.io "hizli-ssd" not found

Exercise Write a PVC

Write a PersistentVolumeClaim YAML: name api-veri; ReadWriteOnce under accessModes; storageClassName: standard; resources.requests.storage: 5Gi.

Show example solution

apiVersion: v1
kind: PersistentVolumeClaim
metadata:
  name: api-veri
spec:
  accessModes:
    - ReadWriteOnce
  storageClassName: standard
  resources:
    requests:
      storage: 5Gi

Test yourself

What is the relationship between a PV and a PVC?
- A PVC is a request; Kubernetes binds a PV matching it
- A PVC is a backup of a PV
- The PV is inside the PVC
- They are unrelated
Show answer

A PVC is a request; Kubernetes binds a PV matching it — Binding is one-to-one: a PV is bound to only one PVC at a time.

Write the requested storage amount.

  resources:
    requests:
      ____: 5Gi

Show answer

  resources:
    requests:
      storage: 5Gi

Match.

PVC

Storage request
PV

Actual storage
Bound

Bound
Pending

Waiting for a suitable PV

Next lesson: StorageClass

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