How to Rebind a StatefulSet to an Existing PVC in Azure Kubernetes Service (AKS)

 

• You deleted the StatefulSet, PVC, PV, and StorageClass, but the Azure File Share still has the data because of the reclaimPolicy: Retain.
• A new PVC was automatically created when you redeployed the StatefulSet, but you want the StatefulSet to use the old PVC (pvc-84031045-6eaa-4680-8c4f-ee32528b17eb) with the retained data instead.

Solution Steps

1. Delete the newly created PVC: First, delete the newly created PVC (pvc-4f8c6892-d973-4213-9325-7ed9ee128772), as you want the StatefulSet to reuse the existing one. This can be done with:

   bash
   kubectl delete pvc pvc-4f8c6892-d973-4213-9325-7ed9ee128772
   

2. Retain the Existing PV: You need to manually reclaim the existing PV (Persistent Volume) that was retained (pvc-84031045-6eaa-4680-8c4f-ee32528b17eb) and bind it to a new PVC. Since the PV is in the Retain state, you'll need to manually associate it with the PVC.

   Here's how to reclaim and rebind it to your StatefulSet:

   • Identify the PV: First, get the list of the Persistent Volumes (PV) and check if the old PV is in the Released state.

     bash
     
     kubectl get pv
     

     The output should list the existing PV with the old PVC name (in Released status):

     bash
     
     NAME                                       CAPACITY   ACCESS MODES   RECLAIM POLICY   STATUS     CLAIM                                             STORAGECLASS       REASON   AGE
     pvc-84031045-6eaa-4680-8c4f-ee32528b17eb   20Gi       RWX            Retain           Released   default/pvc-84031045-6eaa-4680-8c4f-ee32528b17eb   azurefile-csi-custom   10d
     

   • Edit the PV: Edit the PV (pvc-84031045-6eaa-4680-8c4f-ee32528b17eb) and remove the existing claim reference (this is necessary to bind it to a new PVC):

     bash
     
     kubectl edit pv pvc-84031045-6eaa-4680-8c4f-ee32528b17eb
     

     In the PV YAML, you will see a reference to the old PVC under the spec.claimRef section. Delete the entire claimRef section to unbind the PV from the old PVC.

     yaml
     
     spec:
       claimRef:
         apiVersion: v1
         kind: PersistentVolumeClaim
         name: pvc-84031045-6eaa-4680-8c4f-ee32528b17eb
         namespace: default
         uid: 84031045-6eaa-4680-8c4f-ee32528b17eb
     

     Remove this block and save the changes.

3. Create a New PVC: Now that the PV is unbound, create a new PVC that will bind to this existing PV. Create a YAML file for the new PVC, ensuring that the size, storage class, and access mode match the old PV. Here's an example of how the PVC should look:

   yaml
   
   apiVersion: v1
   kind: PersistentVolumeClaim
   metadata:
     name: mssql-data-existing
   spec:
     accessModes:
       - ReadWriteMany  # This should match the old PV's access mode
     storageClassName: azurefile-csi-custom  # This should match the old PV's storage class
     resources:
       requests:
         storage: 20Gi  # This should match the old PV's size
   

   Apply the PVC:

   bash
   
   kubectl apply -f new-pvc.yaml
   

   After the PVC is created, Kubernetes should automatically bind this new PVC to the existing PV (pvc-84031045-6eaa-4680-8c4f-ee32528b17eb) because it matches the size, storage class, and access mode.

   You can verify that the new PVC is bound to the existing PV:

   bash
   
   kubectl get pvc
   

   You should see the new PVC (mssql-data-existing) in the Bound state.

4. Update StatefulSet to Use the Existing PVC: Now that the PVC is bound to the existing PV, update your StatefulSet to reference the existing PVC. In your StatefulSet YAML, replace the volumeClaimTemplates section with a direct reference to the existing PVC:

   yaml
   
   volumeMounts:
   - name: mssql-data
     mountPath: /var/opt/mssql
   
   volumes:
   - name: mssql-data
     persistentVolumeClaim:
       claimName: mssql-data-existing  # The newly bound PVC
   

   Apply the updated StatefulSet:

   bash
   
   kubectl apply -f statefulset.yaml
   

5. Verify the Pod: After deploying the updated StatefulSet, verify that the pod is using the existing PVC:

   bash
   
   kubectl get pods
   

   You can also describe the pod to ensure that the volume is mounted correctly:

   bash
   
   kubectl describe pod <pod-name>
   

   Make sure that the pod is mounting the existing PVC (mssql-data-existing) at /var/opt/mssql.