Longhorn can easily restore backups to a volume.

For more information on how backups work, refer to the concepts section.

When you restore a backup, it creates a volume of the same name by default. If a volume with the same name as the backup already exists, the backup will not be restored.

Restore via Longhorn UI

1. Navigate to the Backup menu.
2. Select the backup(s) you wish to restore and click Restore Latest Backup.
3. In the Name field, select the volume name you wish to create.
4. Click OK.

You can then create the PV/PVC from the volume after restoring a volume from a backup. Here you can specify the storageClassName or leave it empty to use the storageClassName inherited from the PVC of the backup volume. The StorageClass should already be in the cluster to prevent any further issues.

Restore via Custom Resource (CLI)

1. Identify the Backup to Restore

List the available backups to find the name of the backup you wish to restore:

kubectl get backups.longhorn.io -n longhorn-system

2. Retrieve Backup Details

You must obtain the exact Backup URL and the Volume Size (in bytes) from the status of the Backup CR:

# Get the Backup URL
kubectl get backup.longhorn.io <BACKUP-NAME> -n longhorn-system -o jsonpath='{.status.url}'

# Get the Volume Size (in bytes)
kubectl get backup.longhorn.io <BACKUP-NAME> -n longhorn-system -o jsonpath='{.status.volumeSize}'

3. Create the Volume Manifest

Apply a Volume manifest using the details retrieved above.

Important:
The size field must be the exact byte count provided by the backup status, wrapped in double quotes (e.g., "1073741824"). Using Kubernetes quantities like 1Gi or raw integers without quotes will result in an admission webhook error.

apiVersion: longhorn.io/v1beta2
kind: Volume
metadata:
  name: restored-volume-name
  namespace: longhorn-system
spec:
  size: "1073741824" # Must be the exact byte count as a string
  fromBackup: "s3://longhorn-backupstore@us-east-1/?backup=backup-123&volume=pvc-456"
  numberOfReplicas: 3
  frontend: blockdev
  dataEngine: v1

4. Monitor Restore Progress

Before attaching the volume to a workload, verify that the restoration is complete. The volume state should be detached and restoreRequired should be false.

kubectl get volume restored-volume-name -n longhorn-system -o jsonpath='{.status.restoreRequired}'

5. Manually Bind the PV and PVC

Unlike the UI method, restoring via CR requires you to manually create the PersistentVolume (PV) and PersistentVolumeClaim (PVC). The volumeHandle in the PV must match the metadata.name of the Volume CR.

apiVersion: v1
kind: PersistentVolume
metadata:
  name: restored-pv
spec:
  capacity:
    storage: 1Gi # Matches the volume size
  volumeMode: Filesystem
  accessModes: [ReadWriteOnce]
  storageClassName: longhorn
  csi:
    driver: driver.longhorn.io
    volumeHandle: restored-volume-name # Matches Volume CR Name
---
apiVersion: v1
kind: PersistentVolumeClaim
metadata:
  name: restored-pvc
  namespace: default
spec:
  accessModes: [ReadWriteOnce]
  resources:
    requests:
      storage: 1Gi
  volumeName: restored-pv
  storageClassName: longhorn

Result: The restored volume is bound to a PVC and ready for use by your applications.