I'm building a Kubernetes app that writes files to disk. What should I use for persistence?

For a Kubernetes app that writes files to disk, the usual answer is: use a PersistentVolumeClaim (PVC) backed by storage that matches your durability and performance needs.

What to use

1. PersistentVolumeClaim (PVC)

This is the Kubernetes-native way to request persistent storage for a Pod.

• Your app mounts the PVC as a volume.
• The data survives Pod restarts and rescheduling.
• The underlying storage can be:
  • cloud disks like AWS EBS / GCE PD / Azure Disk
  • network storage like NFS / Ceph / EFS / Filestore
  • local disk, if you’re okay with node affinity and limited portability

2. Pick the right storage class

Use a StorageClass that fits your workload:

• Block storage: good for a single writer, databases, file-based apps
• Shared file storage: good if multiple Pods need to read/write the same files
• Local persistent storage: fastest, but tied to one node

Common choices by use case

If only one Pod needs the files

Use:

• PVC + block storage
• Example: AWS EBS, GCE Persistent Disk, Azure Disk

Good for:

• app data
• uploads
• caches that must survive restarts
• file-based state for one instance

If multiple Pods need the same files

Use:

• PVC with ReadWriteMany
• Typically backed by:
  • NFS
  • AWS EFS
  • Azure Files
  • GCP Filestore

Good for:

• shared uploads
• content repositories
• apps scaled horizontally

If you need maximum performance and can tolerate node coupling

Use:

• local persistent volume

Good for:

• high-performance workloads
• temporary-but-persistent local data
• specialized storage needs

What not to use

• emptyDir: data disappears when the Pod is deleted or moved
• writing directly into the container filesystem: also ephemeral
• hostPath in production: usually fragile and node-dependent

Typical recommendation

If you're unsure, start with:

• one Pod → PVC backed by block storage
• multiple Pods sharing files → PVC backed by RWX/shared storage

Example

A simple Pod mount looks like this:

apiVersion: v1
kind: PersistentVolumeClaim
metadata:
  name: app-data
spec:
  accessModes:
    - ReadWriteOnce
  storageClassName: standard
  resources:
    requests:
      storage: 10Gi
---
apiVersion: v1
kind: Pod
metadata:
  name: my-app
spec:
  containers:
    - name: app
      image: my-app:latest
      volumeMounts:
        - mountPath: /data
          name: data
  volumes:
    - name: data
      persistentVolumeClaim:
        claimName: app-data

Rule of thumb

• Need persistence? Use a PVC
• Need sharing across Pods? Use RWX/shared storage
• Need speed and single-node usage? Consider local PV

If you want, I can also recommend the best storage option based on your cloud provider and whether you need one writer or multiple writers.