Dynamically Mounting a DSS Disk to a StatefulSet¶
Application Scenarios¶
Dynamic mounting is available only for creating a StatefulSet. It is implemented through a volume claim template (volumeClaimTemplates field) and depends on dynamic creation of PVs through StorageClass. In this mode, each pod in a multi-pod StatefulSet is associated with a unique PVC and PV. After a pod is rescheduled, the original data can still be mounted to it based on the PVC name. In the common mounting mode for a Deployment, if ReadWriteMany is supported, multiple pods of the Deployment will be mounted to the same underlying storage.
Prerequisites¶
You have created a cluster of version v1.21.15-r0, v1.23.14-r0, v1.25.9-r0, v1.27.6-r0, v1.28.4-r0, or later, and CCE Container Storage (Everest) of v2.4.5 or later has been installed in the cluster.
To create a cluster using commands, ensure kubectl is used. For details, see Connecting to a Cluster Using kubectl.
Dynamically Mounting a DSS Disk on the Console¶
Log in to the CCE console and click the cluster name to access the cluster console.
Choose Workloads in the navigation pane. In the right pane, click the StatefulSets tab.
Click Create Workload in the upper right corner. On the displayed page, click Data Storage in the Container Settings area and click Add Volume to select VolumeClaimTemplate.
Click Create PVC. In the dialog box displayed, configure PVC parameters.
Click Create.
Parameter
Description
PVC Type
In this example, select DSS.
PVC Name
Enter the name of the PVC. After a PVC is created, a suffix is automatically added based on the number of pods. The format is <Custom PVC name>-<Serial number>, for example, example-0.
Creation Method
You can select Dynamically provision to create a PVC, PV, and underlying storage on the console in cascading mode.
Storage Classes
The storage class for DSS disks is csi-disk-dss.
(Optional) Storage Volume Name Prefix
Available only when the cluster version is v1.23.14-r0, v1.25.9-r0, v1.27.6-r0, v1.28.4-r0, or later, and Everest of v2.4.15 or later is installed in the cluster.
This parameter specifies the name of the underlying storage that is automatically created. The actual underlying storage name is in the format of "PV name prefix + PVC UID". If this parameter is left blank, the default prefix pvc will be used.
For example, if the PV name prefix is set to test, the actual underlying storage name is test-{UID}.
DSS Pool
Select an existing DSS pool.
Capacity (GiB)
Capacity of the requested storage volume.
Access Mode
DSS volumes support only ReadWriteOnce, indicating that a storage volume can be mounted to one node in read/write mode.
Encryption
Configure whether to encrypt underlying storage. If you select Enabled (key), an encryption key must be configured.
Resource Tag
You can add resource tags to classify resources, which is supported only when the Everest version in the cluster is 2.1.39 or later.
You can create predefined tags on the TMS console. The predefined tags are available to all resources that support tags. You can use predefined tags to improve the tag creation and resource migration efficiency. For details, see .
CCE automatically creates system tags CCE-Cluster-ID={Cluster ID}, CCE-Cluster-Name={Cluster name}, and CCE-Namespace={Namespace name}. These tags cannot be modified.
Note
After a dynamic PV of the DSS type is created, the resource tags cannot be updated on the CCE console. To update DSS resource tags, go to the DSS console.
Enter the path to which the volume is mounted.
Table 1 Mounting a storage volume¶ Parameter
Description
Mount Path
Enter a mount path, for example, /tmp.
This parameter specifies a container path to which a data volume will be mounted. Do not mount the volume to a system directory such as / or /var/run. Otherwise, containers will be malfunctional. Mount the volume to an empty directory. If the directory is not empty, ensure that there are no files that affect container startup. Otherwise, the files will be replaced, leading to container startup failures or workload creation failures.
Important
NOTICE: If a volume is mounted to a high-risk directory, use an account with minimum permissions to start the container. Otherwise, high-risk files on the host may be damaged.
Subpath
Enter the subpath of the storage volume and mount a path in the storage volume to the container. In this way, different folders of the same storage volume can be used in a single pod. tmp, for example, indicates that data in the mount path of the container is stored in the tmp folder of the storage volume. If this parameter is left blank, the root path is used by default.
Permission
Read-only: You can only read the data in the mounted volumes.
Read-write: You can modify the data volumes mounted to the path. Newly written data will not be migrated if the container is migrated, which may cause data loss.
In this example, the disk is mounted to the /data path of the container. The container data generated in this path is stored in the DSS disk.
Dynamically mount and use storage volumes. For details about other parameters, see Creating a StatefulSet. After the configuration, click Create Workload.
After the workload is created, the data in the container mount directory will be persistently stored. Verify the storage by referring to Verifying Data Persistence.
Dynamically Mounting a DSS Volume Through kubectl¶
Use kubectl to access the cluster.
Create a file named statefulset-dss.yaml. In this example, the disk is mounted to the /data path.
apiVersion: apps/v1 kind: StatefulSet metadata: name: statefulset-dss namespace: default spec: selector: matchLabels: app: statefulset-dss template: metadata: labels: app: statefulset-dss spec: containers: - name: container-1 image: nginx:latest volumeMounts: - name: pvc-disk # The value must be the same as that in the volumeClaimTemplates field. mountPath: /data # Location where the storage volume is mounted imagePullSecrets: - name: default-secret serviceName: statefulset-dss # Headless Service name replicas: 2 volumeClaimTemplates: - apiVersion: v1 kind: PersistentVolumeClaim metadata: name: pvc-disk namespace: default annotations: everest.io/disk-volume-type: SAS # Disk type everest.io/csi.dedicated-storage-id: <dss_id> # ID of the DSS storage pool everest.io/crypt-key-id: <your_key_id> # (Optional) Encryption key ID. Mandatory for an encrypted disk. everest.io/enterprise-project-id: <your_project_id> # (Optional) Enterprise project ID. If an enterprise project is specified, use the same enterprise project when creating a PVC. Otherwise, the PVC cannot be bound to a PV. everest.io/disk-volume-tags: '{"key1":"value1","key2":"value2"}' # (Optional) Custom resource tags everest.io/csi.volume-name-prefix: test # (Optional) PV name prefix of the automatically created underlying storage labels: failure-domain.beta.kubernetes.io/region: <your_region> # Region of the node where the application is to be deployed failure-domain.beta.kubernetes.io/zone: <your_zone> # AZ of the node where the application is to be deployed spec: accessModes: - ReadWriteOnce # The value must be ReadWriteOnce for DSS. resources: requests: storage: 10Gi # Disk capacity, ranging from 1 to 32768 storageClassName: csi-disk # StorageClass is DSS. --- apiVersion: v1 kind: Service metadata: name: statefulset-dss # Headless Service name namespace: default labels: app: statefulset-dss spec: selector: app: statefulset-dss clusterIP: None ports: - name: statefulset-dss targetPort: 80 nodePort: 0 port: 80 protocol: TCP type: ClusterIP
Table 2 Key parameters¶ Parameter
Mandatory
Description
failure-domain.beta.kubernetes.io/region
Yes
Region where the cluster is located.
failure-domain.beta.kubernetes.io/zone
Yes
AZ where the DSS volume is created. It must be the same as the AZ planned for the workload.
everest.io/disk-volume-type
Yes
Disk type. All letters are in uppercase.
SAS: high I/O
SSD: ultra-high I/O
everest.io/csi.dedicated-storage-id
Yes
ID of the DSS storage pool where the DSS disk resides.
To obtain a DSS storage pool ID, log in to the Cloud Server Console. In the navigation pane, choose Dedicated Distributed Storage Service > Storage Pools and click the name of the target storage pool. On the resource pool details page, copy the pool ID.
everest.io/crypt-key-id
No
Mandatory when the DSS disk is encrypted. Enter the encryption key ID selected during disk creation.
To obtain a key ID, log in to the DEW console, locate the key to be encrypted, and copy the key ID.
everest.io/disk-volume-tags
No
This field is optional. It is supported when the Everest version in the cluster is 2.1.39 or later.
You can add resource tags to classify resources.
You can create predefined tags on the TMS console. The predefined tags are available to all resources that support tags. You can use predefined tags to improve the tag creation and resource migration efficiency.
CCE automatically creates system tags CCE-Cluster-ID={Cluster ID}, CCE-Cluster-Name={Cluster name}, and CCE-Namespace={Namespace name}. These tags cannot be modified.
everest.io/csi.volume-name-prefix
No
(Optional) This parameter is available only when the cluster version is v1.23.14-r0, v1.25.9-r0, v1.27.6-r0, v1.28.4-r0, or later, and Everest of v2.4.15 or later is installed in the cluster.
This parameter specifies the name of the underlying storage that is automatically created. The actual underlying storage name is in the format of "PV name prefix + PVC UID". If this parameter is left blank, the default prefix pvc will be used.
Enter 1 to 26 characters that cannot start or end with a hyphen (-). Only lowercase letters, digits, and hyphens (-) are allowed.
For example, if the PV name prefix is set to test, the actual underlying storage name is test-{UID}.
storage
Yes
Requested PVC capacity, in Gi. The value ranges from 1 to 32768.
storageClassName
Yes
The storage class for DSS disks is csi-disk-dss.
Run the following command to create a workload to which the DSS volume is mounted:
kubectl apply -f statefulset-dss.yaml
After the workload is created, the data in the container mount directory will be persistently stored. Verify the storage by referring to Verifying Data Persistence.
Verifying Data Persistence¶
View the deployed application and DSS volume files.
Run the following command to view the created pod:
kubectl get pod | grep statefulset-dss
Expected output:
statefulset-dss-0 1/1 Running 0 45s statefulset-dss-1 1/1 Running 0 28s
Run the following command to check whether the DSS volume has been mounted to the /data path:
kubectl exec statefulset-dss-0 -- df | grep data
Expected output:
/dev/sdd 10255636 36888 10202364 0% /data
Run the following command to check the files in the /data path:
kubectl exec statefulset-dss-0 -- ls /data
Expected output:
lost+found
Run the following command to create a file named static in the /data path:
kubectl exec statefulset-dss-0 -- touch /data/static
Run the following command to check the files in the /data path:
kubectl exec statefulset-dss-0 -- ls /data
Expected output:
lost+found static
Run the following command to delete the pod named web-dss-auto-0:
kubectl delete pod statefulset-dss-0
Expected output:
pod "statefulset-dss-0" deleted
After the deletion, the StatefulSet controller automatically creates a replica with the same name. Run the following command to check whether the files in the /data path have been modified:
kubectl exec statefulset-dss-0 -- ls /data
Expected output:
lost+found static
The static file is retained, indicating that the data in the DSS volume can be stored persistently.