Using an SFS File System Through a Dynamic PV

This section describes how to use storage classes to dynamically create PVs and PVCs for data persistence and sharing in workloads.

Prerequisites

You have created a cluster and installed the CCE Container Storage (Everest) add-on in the cluster.
To create a cluster using commands, ensure kubectl is used. For details, see Connecting to a Cluster Using kubectl.
You have created an SFS file system that is in the same VPC as the cluster.

Automatically Creating an SFS File System Through kubectl

Use kubectl to access the cluster.

Use StorageClass to dynamically create a PVC and PV.

Create the pvc-sfs-auto.yaml file.

apiVersion: v1
kind: PersistentVolumeClaim
metadata:
  name: pvc-sfs-auto
  namespace: default
  annotations: 
    everest.io/crypt-key-id: <your_key_id>      # (Optional) ID of the key for encrypting file systems

    everest.io/crypt-alias: sfs/default         # (Optional) Key name. Mandatory for encrypting volumes.

    everest.io/crypt-domain-id: <your_domain_id>   # (Optional) ID of the tenant to which an encrypted volume belongs. Mandatory for encrypting volumes.


spec:
  accessModes:
    - ReadWriteMany             # The value must be ReadWriteMany for SFS.
  resources:
    requests:
      storage: 1Gi             # SFS volume capacity
  storageClassName: csi-nas    # StorageClass is SFS.

**Table 1** Key parameters
Parameter	Mandatory	Description
storage	Yes	Requested capacity in the PVC, in Gi. For SFS, this field is used only for verification (cannot be empty or 0). Its value is fixed at 1, and any value you set does not take effect for SFS file systems.
everest.io/crypt-key-id	No	This parameter is mandatory when an SFS system is encrypted. Enter the encryption key ID selected during SFS system creation. You can use a custom key or the default key named sfs/default. To obtain a key ID, log in to the DEW console, locate the key to be encrypted, and copy the key ID.
everest.io/crypt-alias	No	Key name, which is mandatory when you create an encrypted volume. To obtain a key name, log in to the DEW console, locate the key to be encrypted, and copy the key name.
everest.io/crypt-domain-id	No	ID of the tenant to which the encrypted volume belongs. This parameter is mandatory for creating an encrypted volume. To obtain a tenant ID, hover the cursor over the username in the upper right corner of the ECS console, choose My Credentials, and copy the account ID.

Run the following command to create a PVC:
```
kubectl apply -f pvc-sfs-auto.yaml
```

Create an application.

Create a file named web-demo.yaml. In this example, the SFS volume is mounted to the /data path.

apiVersion: apps/v1
kind: Deployment
metadata:
  name: web-demo
  namespace: default
spec:
  replicas: 2
  selector:
    matchLabels:
      app: web-demo
  template:
    metadata:
      labels:
        app: web-demo
    spec:
      containers:
      - name: container-1
        image: nginx:latest
        volumeMounts:
        - name: pvc-sfs-volume    # Volume name, which must be the same as the volume name in the volumes field
          mountPath: /data  # Location where the storage volume is mounted
      imagePullSecrets:
        - name: default-secret
      volumes:
        - name: pvc-sfs-volume    # Volume name, which can be customized
          persistentVolumeClaim:
            claimName: pvc-sfs-auto    # Name of the created PVC

Run the following command to create a workload to which the SFS volume is mounted:
```
kubectl apply -f web-demo.yaml
```
After the workload is created, the data in the container mount directory will be persistently stored. Verify the storage by referring to Verifying Data Persistence and Sharing.

Verifying Data Persistence and Sharing

View the deployed application and files.
1. Run the following command to view the created pod:
```
kubectl get pod | grep web-demo
```
  Expected output:
```
web-demo-846b489584-mjhm9   1/1     Running   0             46s
web-demo-846b489584-wvv5s   1/1     Running   0             46s
```
2. Run the following commands in sequence to view the files in the /data path of the pods:
```
kubectl exec web-demo-846b489584-mjhm9 -- ls /data
kubectl exec web-demo-846b489584-wvv5s -- ls /data
```
  If no result is returned for both pods, no file exists in the /data path.
Run the following command to create a file named static in the /data path:
```
kubectl exec web-demo-846b489584-mjhm9 --  touch /data/static
```
Run the following command to check the files in the /data path:
```
kubectl exec web-demo-846b489584-mjhm9 -- ls /data
```
Expected output:
```
static
```
Verify data persistence.
1. Run the following command to delete the pod named web-demo-846b489584-mjhm9:
```
kubectl delete pod web-demo-846b489584-mjhm9
```
  Expected output:
```
pod "web-demo-846b489584-mjhm9" deleted
```
  After the deletion, the Deployment controller automatically creates a replica.
2. Run the following command to view the created pod:
```
kubectl get pod | grep web-demo
```
  The expected output is as follows, in which web-demo-846b489584-d4d4j is the newly created pod:
```
web-demo-846b489584-d4d4j   1/1     Running   0             110s
web-demo-846b489584-wvv5s    1/1     Running   0             7m50s
```
3. Run the following command to check whether the files in the /data path of the new pod have been modified:
```
kubectl exec web-demo-846b489584-d4d4j -- ls /data
```
  Expected output:
```
static
```
  The static file is retained, indicating that the data in the file system can be stored persistently.
Verify data sharing.
1. Run the following command to view the created pod:
```
kubectl get pod | grep web-demo
```
  Expected output:
```
web-demo-846b489584-d4d4j   1/1     Running   0             7m
web-demo-846b489584-wvv5s   1/1     Running   0             13m
```
2. Run the following command to create a file named share in the /data path of either pod: In this example, select the pod named web-demo-846b489584-d4d4j.
```
kubectl exec web-demo-846b489584-d4d4j --  touch /data/share
```
  Check the files in the /data path of the pod.
```
kubectl exec web-demo-846b489584-d4d4j -- ls /data
```
  Expected output:
```
share
static
```
3. Check whether the share file exists in the /data path of another pod (web-demo-846b489584-wvv5s) as well to verify data sharing.
```
kubectl exec web-demo-846b489584-wvv5s -- ls /data
```
  Expected output:
```
share
static
```
  After you create a file in the /data path of a pod, if the file is also created in the /data path of the other pod, the two pods share the same volume.

Related Operations

You can also perform the operations listed in Table 2.

**Table 2** Related operations
Operation	Description	Procedure
Viewing events	View event names, event types, number of occurrences, Kubernetes events, first occurrence time, and last occurrence time of the PVC or PV.	Choose Storage in the navigation pane. In the right pane, click the PVCs or PVs tab. Click View Events in the Operation column of the target PVC or PV to view events generated within one hour (events are retained for one hour).
Viewing a YAML file	View, copy, or download the YAML file of a PVC or PV.	Choose Storage in the navigation pane. In the right pane, click the PVCs or PVs tab. Click View YAML in the Operation column of the target PVC or PV to view or download the YAML.