Use CSI to mount a NAS file system to a sandboxed container

How the direct mount solution works

Examples

The following example describes how to mount a NAS file system to a sandboxed container. In this example, an Apsara File Storage NAS instance is created and a YAML file template is used to create resource objects.

1. Create an Apsara File Storage NAS instance. For more information, see Create a file system.
   Notice The NAS file system must be deployed in the same VPC network as the cluster.
   Obtain the mount target of the NAS file system. Log on to the NAS console, find the created Apsara File Storage NAS. The URL (file-system-id.region.nas.aliyuncs.com) in the Mount Command column is the mount target, as shown in the following figure.

   Note file-system-id.region.nas.aliyuncs.com is the address of the mount target. You can obtain the address of the mount target in the NAS console. Log on to the NAS console, click the name of the NAS file system. In the left-side navigation pane, click Mounting Usage. You can find the address of the mount target in the Mount Command column.
2. Use the following template to create resource objects:
   Notice Replace ${nas-server-address} in the template with the address of the mount target.

   cat <<EOF | kubectl create -f -
   apiVersion: v1
   kind: PersistentVolumeClaim
   metadata:
     name: nas-pvc-csi
     namespace: default
   spec:
     accessModes:
       - ReadWriteMany
     resources:
       requests:
         storage: 5Gi
     selector:
       matchLabels:
         alicloud-pvname: nas-pv-csi
   ---
   apiVersion: v1
   kind: PersistentVolume
   metadata:
     labels:
       alicloud-pvname: nas-pv-csi
     name: nas-pv-csi
   spec:
     accessModes:
       - ReadWriteMany
     capacity:
       storage: 5Gi
     csi:
       driver: nasplugin.csi.alibabacloud.com
       volumeAttributes:
         options: noresvport,nolock
         path: /csi
         server: ${nas-server-address}
         vers: "3"
       volumeHandle: nas-pv-csi
     persistentVolumeReclaimPolicy: Retain
   ---
   apiVersion: apps/v1
   kind: Deployment
   metadata:
     name: deploy-nas-csi
   spec:
     replicas: 2
     selector:
       matchLabels:
         app: busybox
     template:
       metadata:
         labels:
           app: busybox
       spec:
         runtimeClassName: runv
         containers:
           - name: busybox
             image: registry.cn-hangzhou.aliyuncs.com/acs/busybox:v1.29.2
             command: 
             - tail
             - -f
             - /dev/null
             volumeMounts:
               - name: nas-pvc
                 mountPath: "/data"
         restartPolicy: Always
         volumes:
           - name: nas-pvc
             persistentVolumeClaim:
               claimName: nas-pvc-csi
   EOF

3. Run the following commands to obtain the IDs of the created pods and query the type of the file systems that are mounted to the pods:

   kubectl get pods

   kubectl exec -it ${podid} sh

   mount | grep /data | grep nfs

   If the output is not empty, it indicates that the NAS file system is directly mounted to the container.

Comparison of I/O performance in different mount modes

• Input/output operations per second (IOPS) of random reads

  Mount mode	Result
  Host	read: IOPS=24.3k, BW=94.8MiB/s (99.4MB/s)(5687MiB/60004msec)
  CSI plug-in	read: IOPS=26.0k, BW=102MiB/s (107MB/s)(6101MiB/60005msec)
  9PFS	read: IOPS=780, BW=3120KiB/s (3195kB/s)(183MiB/60001msec)

• IOPS of random writes

  Mount mode	Result
  Host	write: IOPS=14.3k, BW=55.9MiB/s (58.6MB/s)(3354MiB/60006msec)
  CSI plug-in	write: IOPS=13.8k, BW=53.8MiB/s (56.4MB/s)(3226MiB/60008msec)
  9PFS	write: IOPS=356, BW=1428KiB/s (1462kB/s)(83.7MiB/60001msec)

• Throughput of random reads

  Mount mode	Result
  Host	read: IOPS=331, BW=331MiB/s (347MB/s)(29.9GiB/92439msec)
  CSI plug-in	read: IOPS=251, BW=252MiB/s (264MB/s)(29.9GiB/121561msec)
  9PFS	read: IOPS=130, BW=130MiB/s (136MB/s)(7861MiB/60422msec)

• Throughput of random writes

  Mount mode	Result
  Host	write: IOPS=507, BW=507MiB/s (532MB/s)(29.9GiB/60372msec)
  CSI plug-in	write: IOPS=508, BW=508MiB/s (533MB/s)(29.9GiB/60255msec)
  9PFS	write: IOPS=1, BW=1500KiB/s (1536kB/s)(88.0MiB/60061msec)

The preceding results show that the throughput and IOPS are almost the same between a NAS file system that is mounted through the host and a NAS file system that is mounted by using CSI. However, a NAS file system that is mounted by using CSI has significant advantages in the IOPS than a NAS file system that is mounted through 9pfs.