Using DSS Through a Dynamic PV¶
CCE allows you to specify a StorageClass to automatically create a DSS disk and the corresponding PV. This function is applicable when no underlying storage volume is available.
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.
Notes and Constraints¶
DSS disks cannot be attached across AZs and cannot be used by multiple workloads, multiple pods of the same workload, or multiple tasks. Data sharing of a shared disk is not supported between nodes in a CCE cluster. If a DSS disk is attached to multiple nodes, I/O conflicts and data cache conflicts may occur. Therefore, select only one pod when creating a Deployment that uses DSS.
If an HPA policy is used to expand the capacity of a workload with a DSS disk attached, new pods cannot be started because the DSS disk cannot attach to them.
Automatically Creating a DSS Volume on the Console¶
Log in to the CCE console and click the cluster name to access the cluster console.
Dynamically create a PVC and PV.
Choose Storage in the navigation pane. In the right pane, click the PVCs tab. Click Create PVC in the upper right corner. In the dialog box displayed, configure PVC parameters.
Parameter
Description
PVC Type
In this example, select DSS.
PVC Name
Enter the PVC name, which must be unique in a namespace.
Creation Method
If no underlying storage is available, select Dynamically provision to create a PVC, PV, and underlying storage on the console in cascading mode.
If underlying storage is available, create a PV or use an existing PV to statically create a PVC. For details, see Using DSS Through a Static PV.
In this example, select Dynamically provision.
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.
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.
Click Create.
You can choose Storage in the navigation pane and view the created PVC and PV on the PVCs and PVs tab pages, respectively.
Create an application.
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 PVC.
Mount and use storage volumes, as shown in Table 1. For details about other parameters, see Workloads.
Table 1 Mounting a storage volume¶ Parameter
Description
PVC
Select an existing DSS volume.
A DSS volume can be mounted to only one workload.
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.
Note
A non-shared DSS disk can be attached to only one workload pod. If there are multiple pods, extra pods cannot start properly. Ensure that the number of workload pods is 1 if a DSS disk is attached.
If multiple workload pods are needed, create a StatefulSet and dynamically mount a PV to each pod. For details, see Dynamically Mounting a DSS Disk to 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.
Automatically Creating a DSS Volume Through kubectl¶
Use kubectl to access the cluster.
Use StorageClass to dynamically create a PVC and PV.
Create the pvc-dss-auto.yaml file.
apiVersion: v1 kind: PersistentVolumeClaim metadata: name: pvc-dss-auto 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/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-dss # StorageClass is DSS.
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 disk 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 PVC:
kubectl apply -f pvc-dss-auto.yaml
Create an application.
Create a file named web-dss-auto.yaml. In this example, the disk is mounted to the /data path.
apiVersion: apps/v1 kind: StatefulSet metadata: name: web-dss-auto namespace: default spec: replicas: 1 selector: matchLabels: app: web-dss-auto serviceName: web-dss-auto # Headless Service name template: metadata: labels: app: web-dss-auto spec: containers: - name: container-1 image: nginx:latest volumeMounts: - name: pvc-disk-dss # Volume name, which must be the same as the volume name in the volumes field mountPath: /data # Location where the storage volume is mounted imagePullSecrets: - name: default-secret volumes: - name: pvc-disk-dss # Volume name, which can be customized persistentVolumeClaim: claimName: pvc-dss-auto # Name of the created PVC --- apiVersion: v1 kind: Service metadata: name: web-dss-auto # Headless Service name namespace: default labels: app: web-dss-auto spec: selector: app: web-dss-auto clusterIP: None ports: - name: web-dss-auto targetPort: 80 nodePort: 0 port: 80 protocol: TCP type: ClusterIP
Run the following command to create a workload to which the DSS volume is mounted:
kubectl apply -f web-dss-auto.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 web-dss-auto
Expected output:
web-dss-auto-0 1/1 Running 0 38s
Run the following command to check whether the DSS volume has been mounted to the /data path:
kubectl exec web-dss-auto-0 -- df | grep data
Expected output:
/dev/sdc 10255636 36888 10202364 0% /data
Run the following command to check the files in the /data path:
kubectl exec web-dss-auto-0 -- ls /data
Expected output:
lost+found
Run the following command to create a file named static in the /data path:
kubectl exec web-dss-auto-0 -- touch /data/static
Run the following command to check the files in the /data path:
kubectl exec web-dss-auto-0 -- ls /data
Expected output:
lost+found static
Run the following command to delete the pod named web-dss-auto-0:
kubectl delete pod web-dss-auto-0
Expected output:
pod "web-dss-auto-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 web-dss-auto-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.