PersistentVolumeClaim (PVC)

PersistentVolumeClaim - storage request from the application. The PVC is created in the namespace and bound to the PV (or causes the PV to be dynamically created).

Where to manage

Namespace → Storage → PersistentVolumeClaims.

Screenshot: PVC list

PVC List

Creating PVC

  1. Storage → PersistentVolumeClaims → + Add PersistentVolumeClaim.
  2. Set the Name of the PVC.
  3. Select Access Mode:
    • ReadWriteOnce (RWO);
    • ReadOnlyMany (ROX);
    • ReadWriteMany (RWX).
  4. Specify Requested storage capacity (for example, 10Gi).
  5. Select StorageClassName from the list created in the cluster.
  6. If necessary, set VolumeName to bind to an existing PV.
  7. If necessary, add a PV Selector (matchLabels) to select PVs by label.
  8. Add PVC labels and annotations as needed.
  9. Click Create.

Required fields when creating a PVC: PVC name, access mode, requested storage volume and StorageClass. The volume is specified in Kubernetes units: bytes (B), kibibytes (Ki), mebibytes (Mi) or gibibytes (Gi).

Access modes

The access mode determines how the PV associated with the PVC can be mounted into pods:

ModeDescriptionWhen to use
ReadWriteOnce (RWO)PV can be mounted read-write on a single node.Suitable for most databases and stateful applications that do not require simultaneous access from multiple nodes.
ReadOnlyMany (ROX)PV can be mounted in read-only mode on multiple nodes.Suitable for general references, static data, and configurations that should not be modified by applications.
ReadWriteMany (RWX)PV can be mounted in read-write mode on multiple nodes.Use only if multiple pods really need a shared volume to write to, such as for NFS/CephFS scenarios.

The availability of a specific mode depends on the StorageClass and CSI driver: not every storage type supports ROX or RWX.

PV and VolumeName selector

  • VolumeName is used to force the PVC to link to a previously created PV. For successful binding, the StorageClass, access mode and volume must match, and from the PV side it must be possible to bind to this PVC.
  • PV selector allows you to specify matchLabels and select only PVs with matching labels.

PVC statuses

StatusDescription
PendingWaiting for binding to PV.
BoundSuccessfully attached to PV.
LostCommunication with PV is lost.

View and delete PVC

The following tabs are available on the PVC page:

  • PVC — main parameters of PVC;
  • PersistentVolumes — associated PV;
  • Labels and annotations;
  • Events — Kubernetes events associated with PVC;
  • Manifest — YAML manifest of PVC.

You can remove PVC in one of the following ways:

  • in the PersistentVolumeClaims list, click the delete icon in the object line;
  • on the PVC page on the PVC tab, click Delete;
  • on the Manifest tab, click the delete icon.

Features of PVC

Volume expansion

In the Shturval platform, after creating a PVC, increase in the requested volume is allowed through the GUI. Expansion is only possible if:

  • StorageClass has allowVolumeExpansion: true;
  • CSI driver supports extension (vSphere, oVirt, Ceph, Cinder, etc.).

How ​​to increase: open PVC → change the requested volume → Save. The file system within the volume may require an extension (for example, resize2fs for ext4).

Limitation: Volume reduction is not supported by Kubernetes.

Delete Delay

If PVC is used in a pod, removal is delayed until the pod frees the volume.

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