storageclass

StorageClass is a Kubernetes resource that describes how dynamic provisioning of persistent storage should be performed. It defines the type of storage backend and the parameters a cluster’s storage provider should use when creating volumes to satisfy PersistentVolumeClaims. A StorageClass does not store data itself; instead, it configures provisioning behavior for a class of storage requests.

Key fields commonly include the provisioner, which identifies the external driver or CSI driver responsible for provisioning, and parameters, a set of backend-specific options such as performance or encryption settings. Other fields include reclaimPolicy (how a PV is treated after the corresponding PVC is deleted, typically Delete or Retain), volumeBindingMode (Immediate or WaitForFirstConsumer), allowVolumeExpansion (whether a PVC can be expanded), and allowedTopologies (to enable topology-aware provisioning).

Usage involves creating a PVC that references a StorageClass by name. If a PVC does not specify a class and a default StorageClass exists, the default may be used automatically. If no default is defined, the claim may remain unprovisioned unless a specific StorageClass is requested. When a PVC is created, the control plane communicates with the designated provisioner to create a PV, which is then bound to the PVC.

Administrators can define multiple StorageClass objects to represent different backends or performance profiles (for example, cloud block storage, NFS, or local disks). StorageClass names are referenced by PVCs via storageClassName. In environments with dynamic provisioning, PVCs can be satisfied automatically; in others, manual PV provisioning may be required. Marking a StorageClass as default through an annotation makes it the target for PVCs that omit a storageClassName.