Mount a NAS file system - Elastic Container Instance - Alibaba Cloud Documentation Center

File Storage NAS (NAS) is a distributed file system provided by Alibaba Cloud. NAS supports shared access and auto scaling. NAS features high reliability and high performance. After you deploy the CSI-Provisioner component provided by Alibaba Cloud on a self-managed Kubernetes cluster, you can mount NAS file systems as volumes on the cluster. You can mount NAS file systems as statically or dynamically provisioned volumes. This topic describes how to use a PersistentVolumeClaim (PVC) to mount a NAS file system to an elastic container instance-based pod.

Prerequisites

A VNode is deployed in a self-managed Kubernetes cluster.
The version of the self-managed Kubernetes cluster is v1.16 or later, and the CSI-Provisioner component is deployed on the self-managed Kubernetes cluster.
Important
For information about how to deploy the CSI-Provisioner component, see alibaba-cloud-csi-driver. If an issue occurs when you deploy the component, submit the issue on GitHub.
If the self-managed Kubernetes cluster is deployed in a data center, the data center is connected to Alibaba Cloud.

Precautions

NAS is a shared storage service. You can mount a NAS file system to multiple pods. If a NAS file system is mounted to multiple pods, the data in the file system is shared by the pods. In this case, an application must be able to synchronize data across these pods when data modifications are made to multiple pods.
Do not delete the mount target before you unmount the NAS file system. Otherwise, an operating system hang may occur.

Mount a NAS file system as a statically provisioned volume

Create a NAS file system and add a mount target.
1. Log on to the NAS console.
2. Create a NAS file system and add a mount target.
  The NAS file system and mount target must reside in the same VPC as the VNode. For more information, see Create a NAS file system and Manage mount targets.

Create a persistent volume (PV).

Create a file named static-nas-pv.yaml and copy the following template into the file. Modify the parameters in the template as required.

apiVersion: v1
kind: PersistentVolume
metadata:
  name: static-nas-pv
  labels:
    alicloud-pvname: static-nas-pv
spec:
  capacity:
    storage: 25Gi
  accessModes:
    - ReadWriteMany
  csi:
    driver: nasplugin.csi.alibabacloud.com
    volumeHandle: static-nas-pv
    volumeAttributes:
      server: "2564f4****-ysu87.cn-beijing.nas.aliyuncs.com"
      path: "/test"
  mountOptions:
  - nolock,tcp,noresvport
  - vers=3

The following table describes the parameters in the template.

Parameter	Description
driver	The type of the driver used. In this example, the parameter is set to `nasplugin.csi.alibabacloud.com`. This indicates that the Container Storage Interface (CSI) plug-in provided by Alibaba Cloud for NAS is used.
volumeHandle	The unique ID of the PV. The value must be the same as the name defined in metadata.
server	The mount point of the NAS file system.
path	The subdirectory of the NAS file system that you want to mount. If you want to mount an Extreme NAS file system, set the parameter to a subdirectory of the `/share` directory. Example: `/share/path1`.
vers	The version number of the Network File System (NFS) protocol that is used to mount the NAS file system. We recommend that you use NFS v3. Extreme NAS supports only NFS v3.

Run the following command to create a PV:
```
kubectl create -f static-nas-pv.yaml
```

Create a PVC.

Create a file named static-nas-pvc.yaml and copy the following template into the file:

apiVersion: v1
kind: PersistentVolumeClaim
metadata:
  name: static-nas-pvc
spec:
  accessModes:
  - ReadWriteMany
  resources:
    requests:
      storage: 25Gi
  selector:
    matchLabels:
      alicloud-pvname: static-nas-pv

Run the following command to create a PVC:
```
kubectl create -f static-nas-pvc.yaml
```

Mount the NAS file system to two elastic container instance-based pods.

Create a file named static-nas-test.yaml and copy the following template into the file:

apiVersion: apps/v1
kind: Deployment
metadata:
  name: static-nas-test
  labels:
    app: nginx
spec:
  replicas: 2
  selector:
    matchLabels:
      app: nginx
  template:
    metadata:
      labels:
        app: nginx
    spec:
      nodeSelector:    
        k8s.aliyun.com/vnode: "true"
      tolerations:     
      - key: k8s.aliyun.com/vnode
        operator: "Equal"
        value: "true"
        effect: "NoSchedule"
      containers:
      - name: nginx
        image: registry-vpc.cn-beijing.aliyuncs.com/eci_open/nginx:1.14.2
        ports:
        - containerPort: 80
        volumeMounts:
          - name: pvc-nas
            mountPath: /data
      volumes:
        - name: pvc-nas
          persistentVolumeClaim:
            claimName: static-nas-pvc

Run the following command to create a Deployment:
```
kubectl create -f static-nas-test.yaml
```

View the results.

kubectl get pods -o wide

The following command output is expected:

NAME                              READY   STATUS    RESTARTS   AGE   IP            NODE                                  NOMINATED NODE   READINESS GATES

static-nas-test-5c4b6d4bd-4kggt   1/1     Running   0          95s   172.16.XX.XX   cn-beijing.vnd-2ze8nd8xcl33t4pa****   <none>           <none>
static-nas-test-5c4b6d4bd-ql6m4   1/1     Running   0          95s   172.16.XX.XX   cn-beijing.vnd-2ze8nd8xcl33t4pa****   <none>           <none>

Check the file directories in the pods and verify that the /data mount directory is generated for the NAS file system. In addition, verify that the files written to the first pod can be viewed in the second pod. This indicates that the two pods share the NAS file system.

Mount a NAS file system as a statically provisioned volume by using CSI

Mount a NAS file system as a dynamically provisioned volume

Create a NAS file system and add a mount target.
1. Log on to the NAS console.
2. Create a NAS file system and add a mount target.
  The NAS file system and mount target must reside in the same VPC as the VNode. For more information, see Create a NAS file system and Manage mount targets.

Create a StorageClass.

Create a file named nas-sc.yaml and copy the following template into the file. Modify the parameters in the template as required. The following table describes the parameters in the template.

apiVersion: storage.k8s.io/v1
kind: StorageClass
metadata:
  name: alicloud-nas-subpath
mountOptions:
- nolock,tcp,noresvport
- vers=3
parameters:
  volumeAs: subpath
  server: "0cd8b4a576-g****.cn-hangzhou.nas.aliyuncs.com:/k8s/"
provisioner: nasplugin.csi.alibabacloud.com
reclaimPolicy: Retain

Parameter	Description
mountOptions	The mount options, such as the NFS version.
volumeAs	The PV type. A value of subpath indicates a subdirectory. In this case, CSI-Provisioner automatically creates a subdirectory of the NAS file system.
server	The mount target of the NAS file system if you set the volumeAs parameter to subpath.
provisioner	The type of the driver used. In this example, the parameter is set to `nasplugin.csi.alibabacloud.com`. This indicates that the CSI plug-in provided by Alibaba Cloud for NAS is used.
reclaimPolicy	The reclaim policy of the PV. Default value: Delete. You can also set this parameter to Retain. Delete: When a PVC is deleted, the related PV and NAS file system are also deleted. Retain: When a PVC is deleted, the related PV and NAS file system are retained and can only be manually deleted. If you require higher data security, we recommend that you use the Retain mode to prevent data loss caused by user errors.

Run the following command to create a StorageClass:
```
kubectl create -f nas-sc.yaml
```

Create a PVC of the NAS type.

Create a file named nas-pvc.yaml and copy the following template into the file:

kind: PersistentVolumeClaim
apiVersion: v1
metadata:
  name: nas-pvc
spec:
  accessModes:
  - ReadWriteMany
  storageClassName: alicloud-nas-subpath
  resources:
    requests:
      storage: 25Gi

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

Mount the NAS file system to two elastic container instance-based pods.

Create a file named nas-test.yaml and copy the following template into the file:

apiVersion: apps/v1
kind: Deployment
metadata:
  name: nas-test
  labels:
    app: nginx
spec:
  replicas: 2
  selector:
    matchLabels:
      app: nginx
  template:
    metadata:
      labels:
        app: nginx
    spec:
      nodeSelector:    
        k8s.aliyun.com/vnode: "true"
      tolerations:     
      - key: k8s.aliyun.com/vnode
        operator: "Equal"
        value: "true"
        effect: "NoSchedule"
      containers:
      - name: nginx
        image: registry-vpc.cn-beijing.aliyuncs.com/eci_open/nginx:1.14.2
        volumeMounts:
          - name: pvc-nas
            mountPath: /data
      volumes:
        - name: pvc-nas
          persistentVolumeClaim:
            claimName: nas-pvc

Run the following command to create a Deployment:
```
kubectl create -f nas-test.yaml
```

View the results.

kubectl get pods -o wide

The following command output is expected:

NAME                              READY   STATUS    RESTARTS   AGE     IP             NODE                                  NOMINATED NODE   READINESS GATES
nas-test-76c54d4b4-f7b88          1/1     Running   0          4m41s   172.16.XX.XX   cn-beijing.vnd-2ze8nd8xcl33t4pa****   <none>           <none>
nas-test-76c54d4b4-lqz4b          1/1     Running   0          4m41s   172.16.XX.XX   cn-beijing.vnd-2ze8nd8xcl33t4pa****   <none>           <none>

Mount a NAS file system as a dynamically provisioned volume by using CSI