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.
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.
Nodes running Ubuntu OS do not support this function if they use the Docker container engine.

Creating an SFS Turbo Volume of the subpath Type

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

Create an SFS Turbo file system in the same VPC and subnet as the cluster.
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.
  - More options are available in everest 1.2.8 or a later version. 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.

Run kubectl create -f sfsturbo-subpath-sc.yaml.
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.
- 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.

Run kubectl create -f sfs-turbo-test.yaml.

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 to the Deployment

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.

Create the Deployment.

kubectl create -f deployment-test.yaml

Dynamically Creating a subpath Volume for a StatefulSet

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 are mapped to each other.
storageClassName: indicates the name of the StorageClass.