Configuring Dynamic PVs

Dynamic volume provisioning allows storage volumes to be created on demand. Dynamic volume provisioning depends on the StorageClass objects. The cluster administrator can define multiple StorageClass objects as required and specify a StorageClass that meets service requirements when declaring a PV or PVC. When applying for resources from Huawei storage devices, Huawei CSI creates storage resources that meet service requirements based on the preset StorageClass.

Configuration Description

Perform the following steps to configure and use dynamic PVs:

Preparation
Configuring a PVC
Using a PVC

Preparation

Before configuring dynamic PVs, configure StorageClass by referring to Configuring a StorageClass .

Configuring a PVC

Prepare the PVC configuration file mypv.yaml. The following is an example. For details about other parameters, see Table 1 .

kind: PersistentVolumeClaim
apiVersion: v1
metadata:
  name: mypvc
spec:
  accessModes:
    - ReadWriteOnce
  volumeMode: Filesystem
  storageClassName: mysc
  resources:
    requests:
      storage: 100Gi

Run the following command to create a PVC using the configuration file.
```
kubectl create -f mypvc.yaml
```
After a period of time, run the following command to view the information about the created PVC.
```
kubectl get pvc mypvc
```
The following is an example of the command output. If the PVC status is Bound, the PVC has been created and can be used by a Pod.
```
NAME        STATUS   VOLUME                                     CAPACITY   ACCESS MODES   STORAGECLASS   AGE
mypvc       Bound    pvc-840054d3-1d5b-4153-b73f-826f980abf9e   100Gi      RWO            mysc           12s
```
- After the PVC is created, if the PVC is in the Pending state after a long time (for example, one minute), refer to When a PVC Is Created, the PVC Is in the Pending State .
- You are advised to create or delete a maximum of 100 PVCs in a batch.

Table 1 PVC parameters for configuring a dynamic PV

Parameter	Description	Mandatory	Default Value	Remarks
metadata.name	User-defined name of a PVC object.	Yes	-	Take Kubernetes v1.22.1 as an example. The value can contain digits, lowercase letters, hyphens (-), and periods (.), and must start and end with a letter or digit.
spec.volumeMode	Volume mode. This parameter is optional. When LUN volumes are used, the following types are supported: Filesystem: local file system. Block: raw device.	No	Filesystem	This parameter takes effect when a PV is mounted. The default value is Filesystem. Filesystem indicates that a container accesses a PV using a local file system. The local file system type is specified by the fsType field in the specified StorageClass. Storage of the Dtree type also uses this parameter. Block indicates that a PV is accessed in raw volume mode.
spec.storageClassName	Name of the StorageClass object.	Yes	-	Name of the StorageClass object required by services.
spec.resources.requests.storage	Size of the volume to be created. The format is ***Gi and the unit is GiB.	Yes	10Gi	The PVC capacity depends on storage specifications and host specifications. For example, OceanStor Dorado 6.1.2 or OceanStor Pacific series 8.1.0 is connected to CentOS 7. If ext4 file systems are used, see Table 2. If XFS file systems are used, see Table 3. If NFS or raw devices are used, the capacity must meet the specifications of the used Huawei storage device model and version. If the PVC capacity does not meet the specifications, a PVC or Pod may fail to be created due to the limitations of storage specifications or host file system specifications.
spec.accessModes	Access mode of the volume. RWO (ReadWriteOnce): A volume can be mounted to a node in read/write mode. This mode also allows multiple Pods running on the same node to access the volume. ROX (ReadOnlyMany): A volume can be mounted to multiple nodes in read-only mode. RWX (ReadWriteMany): A volume can be mounted to multiple nodes in read/write mode. RWOP (ReadWriteOncePod): A volume can only be mounted to a single Pod in read/write mode. Kubernetes 1.22 and later versions support this feature.	Yes	ReadWriteOnce	RWO/ROX/RWOP: supported by all types of volumes. RWOP is supported only by Kubernetes 1.22 and later versions. For versions earlier than Kubernetes 1.29, you need to enable this feature by following the instructions in Enabling the ReadWriteOncePod Feature Gate. The support for RWX is as follows: NAS storage: supported by all volumes SAN storage: supported only by volumes whose volumeMode is set to Block

Table 2 ext4 capacity specifications

Storage Type	Storage Specifications	ext4 Specifications	CSI Specifications
OceanStor Dorado	512 Ki to 256 Ti	50 Ti	512 Ki to 50 Ti
OceanStor Pacific series	64 Mi to 512 Ti	50 Ti	64 Mi to 50 Ti
OceanDisk	512 Ki to 256 Ti	50 Ti	512 Ki to 50 Ti

Table 3 XFS capacity specifications

Storage Type	Storage Specifications	XFS Specifications	CSI Specifications
OceanStor Dorado	512 Ki to 256 Ti	500 Ti	512 Ki to 256 Ti
OceanStor Pacific series	64 Mi to 512 Ti	500 Ti	64 Mi to 500 Ti
OceanDisk	512 Ki to 256 Ti	500 Ti	512 Ki to 256 Ti

Using a PVC

After a PVC is created, you can use the PVC to create a Pod. The following is a simple example of using a PVC. In this example, the created Pod uses the newly created mypvc.

apiVersion: apps/v1
kind: Deployment
metadata:
  name: nginx-deployment
spec:
  selector:
    matchLabels:
      app: nginx
  replicas: 2
  template:
    metadata:
      labels:
        app: nginx
    spec:
      containers: 
      - image: nginx:alpine
        name: container-0 
        volumeMounts: 
        - mountPath: /tmp
          name: pvc-mypvc 
      restartPolicy: Always 
      volumes: 
      - name: pvc-mypvc 
        persistentVolumeClaim: 
          claimName:  mypvc  # name of PVC

If Pods are batch created using PVCs, the Pods are in the ContainerCreating status for a long time, and the huawei-csi-node service is in the OOMKilled status, the memory of the huawei-csi-node service is insufficient. Increase the memory limit of huawei-csi-node by referring to Table 1 .