Container Service for Kubernetes:Expand a NAS volume

Limits

• Only Capacity NAS file systems support quota limits. For more information about the types of NAS file systems, see NAS file system types.

• Statically provisioned NAS volumes cannot be expanded.

• Quotas can be set only for volumes that are mounted by using subdirectories.

• For each file system, you can create quotas for up to 500 directories.

  • You can set an enforcement quota on a directory. If the quota is exceeded, you cannot write data to the directory and an IOError error is prompted at the frontend. The write operations include the operations that are used to increase the length of files, create files, create subdirectories, create special files, and move files to another directory.

  • To prevent potential security risks, we recommend that you evaluate and test restricted quotas before you create the restricted quotas for core business-related directories.

  • A specific period of time is required before an enforcement quota is enabled or disabled due to asynchronous execution at the backend. In most cases, the time period ranges from 5 to 15 minutes.

Example

1. Use the following YAML template to create a StorageClass to provision a NAS volume that has the quota feature and the dynamic expansion feature enabled.

   apiVersion: storage.k8s.io/v1
   kind: StorageClass
   metadata:
     name: alicloud-nas-quota-sc
   mountOptions:
     - nolock,tcp,noresvport
     - vers=3
   parameters:
     volumeAs: subpath
     server: "xxx.cn-hangzhou.nas.aliyuncs.com:/"
     archiveOnDelete: "false"
     path: "/abc"
     volumeCapacity: "true" # The quota feature is enabled for a volume that is dynamically provisioned based on the StorageClass. 
   provisioner: nasplugin.csi.alibabacloud.com
   reclaimPolicy: Delete
   allowVolumeExpansion: true # Enable dynamic volume expansion.

   Parameter	Description
   mountOptions	Set the mount options of the NAS file system in the mountOptions field. For example, you can specify the NFS version that you want to use.
   volumeAs	You can select subpath or filesystem. subpath indicates that a subdirectory is mounted to the cluster. filesystem indicates that a file system is mounted to the cluster.
   server	When you mount a subdirectory of the NAS file system as a persistent volume (PV), this parameter specifies the mount target of the NAS file system.
   archiveOnDelete	This parameter specifies the reclaim policy of backend storage when reclaimPolicy is set to Delete. NAS is a shared storage service. You must set both reclaimPolicy and archiveOnDelete to ensure data security. Default value: true.
   path	The subdirectory of the NAS file system that is mounted. If you mount an Extreme NAS file system, the path must start with /share.
   volumeCapacity	This parameter specifies whether to set a quota. Valid values: true and false. Note If allowVolumeExpansion is set to true, this parameter configuration will not take effect, and the quota will always be enabled.
   provisioner	The provisioner of the PV that is provided by ACK.
   reclaimPolicy	The policy that is used to reclaim the PV. Valid values: Retain: retains the backend storage when the PV and PVC are deleted. The backend storage may be cloud disks. Delete: automatically deletes the backend storage and PV when the PVC is deleted.
   allowVolumeExpansion	This parameter specifies whether volume expansion is supported.

   Note

   To create a StorageClass that sets quotas on the subdirectory of a NAS file system, enable the quota feature by setting either volumeCapacity=true or allowVolumeExpansion=true.

2. Use the following YAML template to create a StatefulSet. The StatefulSet uses a PVC that requests 20 GiB of storage.

   apiVersion: apps/v1
   kind: StatefulSet
   metadata:
     name: nas-sts
   spec:
     selector:
       matchLabels:
         app: busybox
     serviceName: "busybox"
     replicas: 1
     template:
       metadata:
         labels:
           app: busybox
       spec:
         containers:
         - name: busybox
           image: busybox
           command:
           - sleep
           - "3600"
           volumeMounts:
           - name: nas-pvc
             mountPath: /data
     volumeClaimTemplates:
     - metadata:
         name: nas-pvc
       spec:
         accessModes: [ "ReadWriteMany" ]
         storageClassName: "alicloud-nas-quota-sc"
         resources:
           requests:
             storage: 20Gi

Verify GPU memory isolation

1. Run the following command to write 10 GiB of data to the /data directory that is mounted to the StatefulSet created in Step 2.

   dd if=/dev/zero of=10G.txt bs=1M count=10000

2. Wait 5 to 15 minutes and then check the quota details of the subdirectory.

   1. Log on to the NAS console.

   2. In the left-side navigation pane, choose File System > File System List.

   3. Find the NAS file system that you use and click the icon in the Actions column. Then, click Quota Management.

   4. On the Quota Management page, click Manage Quotas in the Actions column.

      The following figure shows that the subdirectory has a quota limit of 20 GiB. The used storage is 9 GiB.

      When the 20-GiB storage is exhausted, the Disk quota exceeded error is prompted if you attempt to write more data to the subdirectory.

3. If the quota is reached, you can manually perform a dynamic volume expansion.

   1. Run the following command to dynamically expand the volume:

      Note

      Dynamic volume expansion does not interrupt the service that has the volume mounted.

      kubectl patch pvc nas-pvc-0 -p '{"spec":{"resources":{"requests":{"storage":"30Gi"}}}}'

   2. Run the following command to query information about the PV:

      kubectl get pv

      Expected output:

      NAME                              CAPACITY  ACCESS MODES   RECLAIM POLICY   STATUS    CLAIM               STORAGECLASS         REASON     AGE
      nas-63c37cc2-b21e-4b56-b26f-****   30Gi          RWX          Delete        Bound    default/nas-pvc-0   alicloud-nas-quota-sc           25m23s

   3. Run the following command to query information about the PVC:

      kubectl get pvc

      Expected output:

      NAME       STATUS   VOLUME                         CAPACITY  ACCESS MODES   STORAGECLASS            AGE
      nas-pvc-0  Bound   nas-63c37cc2-b21e-4b56-b26f-****   30Gi      RWX        alicloud-nas-quota-sc   25m10s