Expand Kubernetes storage

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This how-to guide explains how to safely expand Kubernetes PersistentVolumeClaims (PVCs) used by Hybrid Manager and EDB-managed Postgres services.

For general storage architecture recommendations, see Kubernetes storage best practices. For overall management tasks, see Manage Kubernetes storage.

Important: Storage behavior and expansion processes differ across cloud providers and Kubernetes platforms.

When to expand PVCs

Common reasons to expand PVCs:

  • Postgres database volume is nearing capacity.
  • WAL volume (if used) is filling up.
  • Monitoring or alerting indicates PVC usage approaching threshold (e.g. 80% full).
  • Workload growth requires more storage.

PVCs in Kubernetes do not shrink automatically — proactive expansion is required to avoid out-of-space conditions.

Preconditions for expansion

Ensure that:

  • The StorageClass in use supports allowVolumeExpansion: true.
  • The cloud provider / CSI driver supports online volume expansion.
  • Postgres operator version supports safe expansion workflows (Hybrid Manager operators do in current releases).
  • You understand platform-specific behaviors

Expansion workflow

1. Determine target PVC

Identify the PVC to expand:

  • Postgres data volume (typically named like <cluster-name>-<instance-id>).
  • WAL volume (if used, named like <cluster-name>-<instance-id>-wal).

Use kubectl get pvc -n <namespace> to list PVCs.

2. Review current PVC status

Check current capacity and usage:

  • Use monitoring dashboards or kubectl describe pvc to check Capacity and Used.

Validate that PVC is Bound and not in an error state before proceeding.

3. Edit PVC size

Increase requested size:

  • Edit the PVC resource using kubectl edit pvc <pvc-name> -n <namespace>.
  • Modify the spec.resources.requests.storage field to desired size (must be larger than current).

Example: increase from 100Gi to 200Gi.

4. Validate expansion

Kubernetes will initiate volume expansion:

  • For supported platforms, the underlying cloud volume will resize automatically.
  • The Postgres Pod may need to be restarted for the filesystem to recognize new space.

Verify:

  • PVC Capacity now shows new size.
  • Postgres Pod restarts cleanly and mounts expanded volume.
  • Postgres logs show correct available space (check df -h inside container if needed).

5. Monitor after expansion

After expansion:

  • Monitor volume usage trends.
  • Validate Postgres workload resumes normal operation.
  • Adjust alerting thresholds as needed.

Expansion is usually transparent to applications but always validate Postgres behavior post-expansion.

Troubleshooting

Common issues:

  • Expansion blocked — check StorageClass settings and platform support.
  • Postgres Pod fails to mount expanded volume — check CSI driver logs and platform events.
  • Filesystem does not recognize new space — Pod restart may be required on some platforms.
  • Expansion takes longer than expected — check cloud provider volume resize status.

See Troubleshooting Kubernetes for general patterns.

Summary checklist

  • Identify PVC to expand and validate preconditions.
  • Edit PVC and increase spec.resources.requests.storage.
  • Monitor expansion progress and validate new capacity.
  • Validate Postgres application behavior after expansion.
  • Monitor and adjust alerting post-expansion.

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