Container Service for Kubernetes:Mount a statically provisioned NAS volume

Usage notes

• NAS is a shared storage service. A single NAS volume can be mounted to multiple pods. If multiple pods write data simultaneously, applications must independently ensure data consistency.

  For more information about the limits on concurrent writes to NAS, see How do I prevent exceptions that may occur when multiple processes or clients concurrently write data to a log file? and How do I resolve the latency in writing data to an NFS file system?

• If your application template includes the securityContext.fsgroup parameter, kubelet performs chmod or chown operations after mounting, which can increase mount time.

  Avoid this setting to reduce latency. For more details, see Extended mount times for NAS volumes.

• Do not delete the NAS mount target after mounting. Doing so may cause the system to become unresponsive.

Mount a statically provisioned NAS volume (using kubectl)

Step 3: Create an application and mount the NAS volume

1. Save the following YAML as nas.yaml:

   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:
         containers:
         - name: nginx
           image: anolis-registry.cn-zhangjiakou.cr.aliyuncs.com/openanolis/nginx:1.14.1-8.6
           ports:
           - containerPort: 80
           volumeMounts:
             - name: pvc-nas
               mountPath: "/data"
         volumes:
           - name: pvc-nas
             persistentVolumeClaim:
               claimName: pvc-nas

   Parameter	Description
   mountPath	Container path where the NAS volume is mounted.
   claimName	Name of the PVC to bind.

2. Deploy the application:

   kubectl create -f nas.yaml

3. Check pod status:

   kubectl get pod -l app=nginx

   Expected output:

   NAME                  READY   STATUS    RESTARTS   AGE
   nas-test-****-***a    1/1     Running   0          32s
   nas-test-****-***b    1/1     Running   0          32s

Mount a statically provisioned NAS volume (using console)

Step 1: Create a PV

1. Log on to the ACK console. In the left navigation pane, click Clusters.

2. On the Clusters page, find the cluster you want and click its name. In the left navigation pane, choose Volumes > Persistent Volumes.

3. On the Persistent Volumes page, click Create.

4. In the dialog box that appears, configure the parameters.

   Parameter		Description	Example
   PV Type		Select NAS.	NAS
   Volume Name		The name of the volume. The name must be unique in the cluster.	pv-nas
   Capacity		The capacity of the PV. Important The actual available capacity is determined by the NAS file system specifications, not this value. See General-purpose NAS and Extreme NAS for details.	5Gi
   Access Mode		Choose ReadWriteMany or ReadWriteOnce.	ReadWriteMany
   Enable CNFS		Specify whether to enable Container Network File System (CNFS). Using CNFS to manage NAS can improve the performance and Quality of Service (QoS) control of NAS. This guide uses direct NAS mounting. For more information about how to configure an existing NAS file system with CNFS, see Use CNFS to manage NAS file systems (recommended).	Disable
   Mount Target Domain Name		Required when CNFS is disabled. Select Select Mount Target or Custom to configure the NAS file system that you want to mount. For details on how to view the mount target address, see Manage mount targets.	0c47****-mpk25.cn-shenzhen.nas.aliyuncs.co
   Advanced Options (Optional)	Mount Path	Subdirectory in the NAS file system to mount. If not set, defaults to root (/for General-purpose NAS, /share for Extreme NAS). If the directory doesn't exist, it will be created. Note For Extreme NAS, paths must start with /share, such as /share/data.	/data
   	Reclaim Policy	The default value is Retain. This indicates that when a PVC is deleted, the related PV and NAS file system are retained and can only be manually deleted. Note Delete must be used with archiveOnDelete. Because static PVs do not support archiveOnDelete, when you select Delete here, the PV and NAS file system are not actually deleted when the PVC is deleted. If you want to configure archiveOnDelete, use a dynamically provisioned NAS volume.	Retain
   	Mount Options	NAS mount parameter, including NFS protocol version. We recommend using NFS v3 protocol, because Extreme NAS only supports NFS v3. For more information about the NFS protocol, see NFS protocol.	nolock,tcp,noresvport vers=3
   Label		Optional labels for the PV.	pv-nas

   Click Create. The PV appears on the Persistent Volumes page.

Step 2: Create a PVC

1. In the left-side navigation pane of the details page, choose Volumes > Persistent Volume Claims.

2. On the Persistent Volume Claims page, click Create.

3. In the dialog box that appears, configure the parameters and click Create.

   Parameter	Description	Example
   Storage Claim Type	Select NAS.	NAS
   Name	The name of the PVC. The name must be unique in the cluster.	pvc-nas
   Allocation Mode	Select Existing Volumes. Note If no PV is created, you can set the Allocation Mode parameter to Create Volume and configure the required parameters to create a PV.	Select Existing Volumes
   Existing Storage Volume	Click Select Existing Volume, find the PV that you want to use, and click Select in the Actions column.	pv-nas
   Capacity	The capacity of the PV. The claimed capacity cannot exceed the total capacity of the PV. Important The actual available capacity is determined by the NAS file system specifications, not this value. See General-purpose NAS and Extreme NAS for details.	5
   Access Mode	The default value is ReadWriteMany. You can also set the value to ReadWriteOnce or ReadOnlyMany.	ReadWriteMany

Step 3: Create an application and mount the NAS volume

1. In the navigation pane on the left of the cluster details page, go to Workloads > Deployments.

2. On the Deployments page, click Create From Image.

3. Configure the parameters of the application. After doing so, click Create.

   The following table describes the key parameters. Use default settings for other parameters. For more information, see Create a stateless application using a Deployment.

   Section	Parameter	Description	Example
   Basic Information	Name	Enter a custom name for the Deployment. The name must meet the format requirements displayed in the console.	nas-test
   	Replicas	Number of pod replicas.	2
   Container	Image Name	Container image.	anolis-registry.cn-zhangjiakou.cr.aliyuncs.com/openanolis/nginx:1.14.1-8.6
   	Required Resources	CPU and memory.	0.25 Core, 512 MiB
   	Volume	Click Add PVC and configure the parameters. Mount Source: Select the PVC that you created. Container Path: Specify the container path to which you want to mount the NAS file system.	Mount Source: pvc-nas Container Path: /data

4. View the application deployment status.

   1. On the Deployments page, click the name of the application.

   2. On the Pods tab, confirm pods are in the Running state.

Verify the shared storage and persistent storage features of NAS

The Deployment created in the preceding example provisions two pods and mounts a NAS file system to the pods. You can use the following methods to verify this:

• Create a file in one pod and view the file from the other pod to verify shared storage.

• Recreate the Deployment. Then, check whether data stored in the file system exists in the newly created pod to verify persistent storage.

1. View the pod information.

   kubectl get pod | grep nas-test

   Sample result:

   nas-test-*****a   1/1     Running   0          40s
   nas-test-*****b   1/1     Running   0          40s

2. Verify shared storage.

   1. Create a file in a pod.

      In this example, the nas-test-*****a pod is used:

      kubectl exec nas-test-*****a -- touch /data/test.txt

   2. View the file from the other pod.

      In this example, the nas-test-*****b pod is used:

      kubectl exec nas-test-*****b -- ls /data

      Expected output shows that the newly created file test.txt is shared:

      test.txt

3. Verify persistent storage.

   1. Recreate the Deployment.

      kubectl rollout restart deploy nas-test

   2. Wait until the pods are recreated.

      kubectl get pod | grep nas-test

      Sample result:

      nas-test-*****c   1/1     Running   0          67s
      nas-test-*****d   1/1     Running   0          49s

   3. Log on to a recreated pod and check whether the file still exists in the file system.

      In this example, the nas-test-*****c pod is used:

      kubectl exec nas-test-*****c -- ls /data

      The following output shows that the file still exists in the NAS file system and can be accessed from the mount directory in the recreated pod.

      test.txt

FAQs

If you encounter issues when mounting or using NAS volumes, refer to:

• Troubleshoot storage issues

• NAS volume FAQ

• FAQ about read and write access to files

References

CNFS enables independent management of NAS file systems, improving performance and QoS control. For best practices, see Use CNFS to manage NAS file systems (recommended).