Infrastructure & Operations › Kubernetes & Orchestration

Persistent Volume

Storage that survives pod restarts.

Also known as: persistent volume, PV PVC, storageclass

Pods are disposable: their containers and writable layer vanish when they’re replaced (see ephemeral filesystem). A PersistentVolume is storage that outlives a pod, so a database, an upload directory or a log archive survives restarts and rescheduling.

Three objects work together:

• PersistentVolume (PV) — a piece of storage, provisioned from a cloud disk, network storage, or a host path.
• PersistentVolumeClaim (PVC) — a request from a pod for a certain size and access mode. The pod mounts the claim; Kubernetes binds it to a volume.
• StorageClass — defines how to provision, so a claim can create storage on demand instead of an admin pre-making volumes.

apiVersion: v1
kind: PersistentVolumeClaim
metadata: { name: data }
spec:
  accessModes: [ReadWriteOnce]
  resources:
    requests: { storage: 20Gi }

A StatefulSet uses a claim template to give each replica its own volume, so pod db-0 always gets its own disk.

The classic mistakes:

• Using hostPath for real data. It ties the volume to one node’s disk and isn’t portable; rescheduled pods may not find it. Use a provisioned volume from a StorageClass instead.
• Deleting the claim by accident. Whether deleting a PVC deletes the underlying disk depends on the storage class’s reclaim policy. With the wrong policy, an accidental delete wipes data — check it, and gate deletions.
• Expecting access modes to mean more than they do. ReadWriteOnce is typically single-node, ReadWriteMany needs storage that supports it. Not every backend offers ReadWriteMany, and assuming it can leave claims stuck Pending.
• Thinking a PV is a backup. It’s live storage, not a copy. Keep backups and consider storage lifecycle for object storage.

When you need it: any workload with state — databases, queues, file storage. Stateless services should avoid it entirely. Match the volume’s performance and durability to the data, and treat the reclaim policy as a decision, not a default.