Background

The minimum capacity of an SFS Turbo file system is 500 GB, 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.

Notes and Constraints

Only clusters of v1.15 and 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 1.2.69 or later or 2.1.11 or later is recommended.

Creating an SFS Turbo Volume of the subpath Type

Do not expand, disassociate, or delete subPath volumes.

Import an SFS Turbo file system that is located in the same VPC and subnet as the cluster.
Create a StorageClass YAML file, for example, sfsturbo-sc-test.yaml.
Configuration example:
```
apiVersion: storage.k8s.io/v1
allowVolumeExpansion: true
kind: StorageClass
metadata:
  name: sfsturbo-sc-test
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: name of the StorageClass.
- mountOptions: 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 Setting Mount Options. Do not set nolock to true. Otherwise, the mount operation fails.
```
mountOptions:
- vers=3
- timeo=600
- nolock
- hard
```
- everest.io/volume-as: Set this parameter to subpath.
- everest.io/share-access-to: This parameter is optional. In subpath mode, 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: root directory to be mounted. It consists of the SFS Turbo shared path and sub-directory. The shared path can be queried on the SFS Turbo console. The sub-directory is user-defined. The PVCs created by the StorageClass are located in the 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: ID of the SFS Turbo volume. You can query the volume ID on the SFS Turbo page.
- everest.io/archive-on-delete: If this parameter is set to true and the recycling policy is set to Delete, the original PV file will be archived when the PVC is deleted. The archive directory is named in the format of archived-$PV name.timestamp. If this parameter is set to false, the SFS Turbo sub-directory corresponding to the PV will be deleted. The default value is true.

Run the kubectl create -f sfsturbo-sc-test.yaml command to create a StorageClass.
Create a PVC YAML file named sfs-turbo-test.yaml.
Configuration example:
```
apiVersion: v1
kind: PersistentVolumeClaim
metadata:
  name: sfs-turbo-test
  namespace: default
spec:
  accessModes:
  - ReadWriteMany
  resources:
    requests:
      storage: 50Gi
  storageClassName: sfsturbo-sc-test
  volumeMode: Filesystem
```
In this example:
- name: name of the PVC.
- storageClassName: name of the StorageClass created in the previous step.
- storage: In the subpath mode, this parameter is invalid. 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 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. You need to ensure that the total capacity of the SFS Turbo file system is not used up.

Creating a Deployment and Mounting an Existing Volume

Create a Deployment YAML file named deployment-test.yaml.

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

Run the kubectl create -f deployment-test.yaml command to create a Deployment.

Creating a StatefulSet That Uses a Volume Dynamically Created in subpath Mode

Create a StatefulSet YAML file named statefulset-test.yaml.