Dynamically Creating and Mounting Subdirectories of an SFS Turbo File System

Background

The minimum capacity of an SFS Turbo file system is 500 GiB, and the SFS Turbo file system cannot be billed by usage. By default, the root directory of an SFS Turbo file system is mounted to a container which, in most case, does not require such a large capacity.

The everest add-on allows you to dynamically create subdirectories in an SFS Turbo file system and mount these subdirectories to containers. In this way, an SFS Turbo file system can be shared by multiple containers to increase storage efficiency.

Constraints

• Only clusters of v1.15 or later are supported.
• The cluster must use the everest add-on of version 1.1.13 or later.
• Kata containers are not supported.
• When the everest add-on earlier than 1.2.69 or 2.1.11 is used, a maximum of 10 PVCs can be created concurrently at a time by using the subdirectory function. everest of 1.2.69 or later or of 2.1.11 or later is recommended.

Creating an SFS Turbo Volume of the subpath Type

Do not expand, disassociate, or delete a subpath volume.

1. Create an SFS Turbo file system in the same VPC and subnet as the cluster.
2. Create a YAML file of StorageClass, for example, sfsturbo-subpath-sc.yaml.

   The following is an example:

   apiVersion: storage.k8s.io/v1
   allowVolumeExpansion: true
   kind: StorageClass
   metadata:
     name: sfsturbo-subpath-sc
   mountOptions:
   - lock
   parameters:
     csi.storage.k8s.io/csi-driver-name: sfsturbo.csi.everest.io
     csi.storage.k8s.io/fstype: nfs
     everest.io/archive-on-delete: "true"
     everest.io/share-access-to: 7ca2dba2-1234-1234-1234-626371a8fb3a
     everest.io/share-expand-type: bandwidth
     everest.io/share-export-location: 192.168.1.1:/sfsturbo/
     everest.io/share-source: sfs-turbo
     everest.io/share-volume-type: STANDARD
     everest.io/volume-as: subpath
     everest.io/volume-id: 0d773f2e-1234-1234-1234-de6a35074696
   provisioner: everest-csi-provisioner
   reclaimPolicy: Delete
   volumeBindingMode: Immediate

   In this example:

   • name: indicates the name of the StorageClass.
   • mountOptions: indicates the mount options. This field is optional.
     • In versions later than everest 1.1.13 and earlier than everest 1.2.8, only the nolock parameter can be configured. By default, the nolock parameter is used for the mount operation and does not need to be configured. If nolock is set to false, the lock field is used.
     • Starting from everest 1.2.8, more mount options are supported. For details, see Configuring SFS Turbo Mount Options. Do not set nolock to true. Otherwise, the mount operation will fail.

       mountOptions:
       - vers=3
       - timeo=600
       - nolock
       - hard

   • everest.io/volume-as: This parameter is set to subpath to use the subpath volume.
   • everest.io/share-access-to: This parameter is optional. In a subpath volume, set this parameter to the ID of the VPC where the SFS Turbo file system is located.
   • everest.io/share-expand-type: This parameter is optional. If the type of the SFS Turbo file system is SFS Turbo Standard – Enhanced or SFS Turbo Performance – Enhanced, set this parameter to bandwidth.
   • everest.io/share-export-location: This parameter indicates the mount directory. It consists of the SFS Turbo shared path and sub-directory. The shared path can be obtained on the SFS Turbo console. The sub-directory is user-defined. The PVCs created using the StorageClass are located in this sub-directory.
   • everest.io/share-volume-type: This parameter is optional. It specifies the SFS Turbo file system type. The value can be STANDARD or PERFORMANCE. For enhanced types, this parameter must be used together with everest.io/share-expand-type (whose value should be bandwidth).
   • everest.io/zone: This parameter is optional. Set it to the AZ where the SFS Turbo file system is located.
   • everest.io/volume-id: This parameter indicates the ID of the SFS Turbo volume. You can obtain the volume ID on the SFS Turbo page.
   • everest.io/archive-on-delete: If this parameter is set to true and Delete is selected for Reclaim Policy, the original documents of the PV will be archived to the directory named archived-{$PV name.timestamp} before the PVC is deleted. If this parameter is set to false, the SFS Turbo subdirectory of the corresponding PV will be deleted. The default value is true, indicating that the original documents of the PV will be archived to the directory named archived-{$PV name.timestamp} before the PVC is deleted.

3. Run kubectl create -f sfsturbo-subpath-sc.yaml.
4. Create a PVC YAML file named sfs-turbo-test.yaml.

   The following is an example:

   apiVersion: v1
   kind: PersistentVolumeClaim
   metadata:
     name: sfs-turbo-test
     namespace: default
   spec:
     accessModes:
     - ReadWriteMany
     resources:
       requests:
         storage: 50Gi
     storageClassName: sfsturbo-subpath-sc
     volumeMode: Filesystem

   In this example:

   • name: indicates the name of the PVC.
   • storageClassName: specifies the name of the StorageClass created in the previous step.
   • storage: In the subpath mode, it is useless to specify this parameter. The storage capacity is limited by the total capacity of the SFS Turbo file system. If the total capacity of the SFS Turbo file system is insufficient, expand the capacity on the SFS Turbo page in a timely manner.

5. Run the kubectl create -f sfs-turbo-test.yaml command to create a PVC.

It is meaningless to conduct capacity expansion on an SFS Turbo volume created in the subpath mode. This operation does not expand the capacity of the SFS Turbo file system. Ensure that the total capacity of the SFS Turbo file system is not used up.

Creating a Deployment and Mounting an Existing Volume

1. Create a YAML file for the Deployment, for example, deployment-test.yaml.
   The following is an example:

   apiVersion: apps/v1
   kind: Deployment
   metadata:
     name: test-turbo-subpath-example
     namespace: default
     generation: 1
     labels:
       appgroup: ''
   spec: 
     replicas: 1 
     selector: 
       matchLabels: 
         app: test-turbo-subpath-example 
     template: 
       metadata: 
         labels: 
           app: test-turbo-subpath-example 
       spec: 
         containers: 
         - image: nginx:latest 
           name: container-0 
           volumeMounts: 
           - mountPath: /tmp
             name: pvc-sfs-turbo-example 
         restartPolicy: Always 
         imagePullSecrets:
         - name: default-secret
         volumes: 
         - name: pvc-sfs-turbo-example 
           persistentVolumeClaim: 
             claimName: sfs-turbo-test

   In this example:

   • name: indicates the name of the Deployment.
   • image: specifies the image used by the Deployment.
   • mountPath: indicates the mount path of the container. In this example, the volume is mounted to the /tmp directory.
   • claimName: indicates the name of an existing PVC.

2. Create the Deployment.

   kubectl create -f deployment-test.yaml

Dynamically Creating a subpath Volume for a StatefulSet

1. Create a YAML file for a StatefulSet, for example, statefulset-test.yaml.

   The following is an example:

   apiVersion: apps/v1
   kind: StatefulSet
   metadata:
     name: test-turbo-subpath
     namespace: default
     generation: 1
     labels:
       appgroup: ''
   spec:
     replicas: 2
     selector:
       matchLabels:
         app: test-turbo-subpath
     template:
       metadata:
         labels:
           app: test-turbo-subpath
         annotations:
           metrics.alpha.kubernetes.io/custom-endpoints: '[{"api":"","path":"","port":"","names":""}]'
           pod.alpha.kubernetes.io/initialized: 'true'
       spec:
         containers:
           - name: container-0
             image: 'nginx:latest'
             resources: {}
             volumeMounts:
               - name: sfs-turbo-160024548582479676
                 mountPath: /tmp
             terminationMessagePath: /dev/termination-log
             terminationMessagePolicy: File
             imagePullPolicy: IfNotPresent
         restartPolicy: Always
         terminationGracePeriodSeconds: 30
         dnsPolicy: ClusterFirst
         securityContext: {}
         imagePullSecrets:
           - name: default-secret
         affinity: {}
         schedulerName: default-scheduler
     volumeClaimTemplates:
       - metadata:
           name: sfs-turbo-160024548582479676
           namespace: default
           annotations: {}
         spec:
           accessModes:
             - ReadWriteOnce
           resources:
             requests:
               storage: 10Gi
           storageClassName: sfsturbo-subpath-sc
     serviceName: wwww
     podManagementPolicy: OrderedReady
     updateStrategy:
       type: RollingUpdate
     revisionHistoryLimit: 10

   In this example:

   • name: indicates the name of the StatefulSet.
   • image: specifies the image used by the StatefulSet.
   • mountPath: indicates the mount path of the container. In this example, the volume is mounted to the /tmp directory.
   • spec.template.spec.containers.volumeMounts.name and spec.volumeClaimTemplates.metadata.name: must be consistent because they have a mapping relationship.
   • storageClassName: indicates the name of the StorageClass.

2. Create the StatefulSet.

   kubectl create -f statefulset-test.yaml