Static Volume Provisioning

1: PV Parameters for Static Volume Provisioning
2: PVC Parameters for Static Volume Provisioning

Static volume provisioning allows administrators to use a resource created on the storage side as a PV for containers in the cluster.

To implement static volume provisioning, perform the following steps:

Configuring a PV
Configuring a PVC

Prerequisites

A storage resource, such as a LUN or file system, required by the PV to be created exists on the storage device. If the storage resource is a file system, you also need to create the share and client information of the file system.

Configuring a PV

Prepare the PV configuration file mypv.yaml. The following is an example. For details about other parameters, see PV Parameters for Static Volume Provisioning.

kind: PersistentVolume
apiVersion: v1
metadata:
  name: mypv
spec:
  volumeMode: Filesystem
  storageClassName: "" # The value must be to "".
  accessModes:
    - ReadWriteOnce
  csi:
    driver: csi.huawei.com # Enter the CSI driver name.
    volumeHandle: iscsi-dorado-181.lun0001 # Enter the volume name.
    fsType: xfs # Set the file system type.
  capacity:
    storage: 100Gi

In the configuration file for static volume provisioning, storageClassName must be set to "". Otherwise, Kubernetes will use the default StorageClass.

Run the following command to create a PV based on the prepared .yaml file.
```
kubectl create -f mypv.yaml
```

After a period of time, run the following command to view the information about the created PV.

kubectl get pv

The following is an example of the command output. If the PV status is Available, the PV is successfully created.

NAME       CAPACITY   ACCESS MODES   RECLAIM POLICY   STATUS      CLAIM               STORAGECLASS   REASON   AGE
mypv       100Gi      RWO            Retain           Available                                               4s

Configuring a PVC

After a PV is created in static volume provisioning mode, you can create a PVC based on the PV for containers.

Prepare the PVC configuration file. The following example is a PVC configuration file for static volume provisioning.

kind: PersistentVolumeClaim
apiVersion: v1
metadata:
  name: mypvc
spec:
  storageClassName: ""
  accessModes:
    - ReadWriteOnce
  volumeMode: Filesystem
  resources:
    requests:
      storage: 100Gi
  volumeName: mypv # Enter the name of the corresponding PV.

Run the following command to create a PVC based on the configured .yaml 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
```
The following is an example of the command output. If the PVC status is Bound, the PVC is successfully created.
```
NAME        STATUS   VOLUME                                     CAPACITY   ACCESS MODES   STORAGECLASS   AGE
mypvc       Bound    pvc-840054d3-1d5b-4153-b73f-826f980abf9e   100Gi      RWO                           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.

Using a PVC

The use method is the same as that for dynamic volume provisioning in Using a PVC.

1 - PV Parameters for Static Volume Provisioning

Table 1 Static volume provisioning parameters

Parameter	Description	Mandatory	Default Value	Remarks
metadata.name	User-defined name of a PV 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. Block indicates that a PV is accessed in raw volume mode.
spec.storageClassName	Name of the StorageClass object. This parameter is mandatory.	Yes	-	Set the parameter to an empty string, that is, enter "".
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. Check whether this feature is enabled for your Kubernetes cluster by referring to 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
spec.csi.driver	CSI driver name.	Yes	csi.huawei.com	Set this parameter to the driver name set during Huawei CSI installation.
spec.csi.volumeHandle	Unique identifier of a storage resource. This parameter is mandatory. Format: <backendName>.<volume-name>	Yes	-	The value of this parameter consists of the following parts: <backendName>: indicates the name of the backend where the volume resides. You can run the following command to obtain the configured backend information. oceanctl get backend <volume-name>: indicates the name of a resource (LUN/file system) on the storage. You can obtain the value from DeviceManager.
spec.csi.fsType	Type of a host file system. This parameter is optional. The supported types are: ext2 ext3 ext4 xfs	No	-	If this parameter is not set, the default value ext4 is used. This parameter is available only when volumeMode is set to Filesystem.
spec.capacity.storage	Volume size.	Yes	100Gi	Ensure that the size is the same as that of the corresponding resource on the storage. Kubernetes will not invoke CSI to check whether the value of this parameter is correct. Therefore, the PV can be successfully created even if its capacity is inconsistent with that of the corresponding resource on the storage.
spec.mountOptions.nfsvers	NFS mount option on the host. The following mount option is supported: nfsvers: protocol version for NFS mounting. The value can be 3, 4, 4.0, 4.1, or 4.2.	No	-	This parameter is optional after the -o parameter when the mount command is executed on the host. The value is in list format. If the NFS version is specified for mounting, NFS 3, 4.0, 4.1, and 4.2 protocols are supported (the protocol must be supported and enabled on storage devices). If nfsvers is set to 4, the latest protocol version NFS 4 may be used for mounting due to different OS configurations, for example, 4.2. If the 4.0 protocol is required, you are advised to set nfsvers to 4.0.
spec.mountOptions.acl	The DPC namespace supports the ACL function. The DPC client supports POSIX ACL, NFSv4 ACL, and NT ACL authentication.	No	-	The descriptions of acl, aclonlyposix, cnflush, and cflush are for reference only. For details about the parameters, see OceanStor Pacific Series Product Documentation and choose Configuration > Basic Service Configuration Guide for File > Configuring Basic Services (DPC Scenario) > Accessing a DPC Share on a Client > Step 2.
spec.mountOptions.aclonlyposix	The DPC namespace supports POSIX ACL, and the DPC client supports POSIX ACL authentication. The following protocols support POSIX ACL: DPC, NFSv3, and HDFS. If NFSv4 ACL or NT ACL is used, the DPC client cannot identify the ACL of this type. As a result, the ACL of this type does not take effect.	No	-	If aclonlyposix and acl are used together, only acl takes effect. That is, the namespace supports the ACL function.
spec.mountOptions.cnflush	Asynchronous disk flushing mode. That is, data is not flushed to disks immediately when files in the namespace are closed.	No	-	Asynchronous flushing mode: When a file is closed, data in the cache is not flushed to storage media in synchronous mode. Instead, data is written from the cache to the storage media in asynchronous flushing mode. After the write service is complete, data is flushed from the cache to disks periodically based on the flushing period. In a multi-client scenario, if concurrent operations are performed on the same file, the file size update is affected by the disk flushing period. That is, the file size is updated only after the disk flushing is complete. Generally, the update is completed within several seconds. Synchronous I/Os are not affected by the disk flushing period.
spec.mountOptions.cflush	Synchronous disk flushing mode. That is, data is flushed to disks immediately when files in the namespace are closed.	No	-	By default, the synchronous disk flushing mode is used.

2 - PVC Parameters for Static Volume Provisioning

Table 1 PVC parameters

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.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. Check whether this feature is enabled for your Kubernetes cluster by referring to 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
spec.volumeMode	Volume mode.	No	Filesystem	This parameter is optional. The value can be Filesystem or Block. The default value is Filesystem. This parameter takes effect when a Pod is created. Filesystem indicates that a file system is created on a PVC to access the storage. Block indicates that a raw volume is used to access the storage.
spec.resources.requests.storage	Size of the volume to be created.	Yes	-	Size of the volume to be created. The format is ***Gi and the unit is GiB. 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. When a PVC is created using a static PV and the PVC capacity is smaller than the capacity of the bound PV, the PVC capacity is set to the capacity of the bound PV. If the PVC capacity is greater than the capacity of the bound PV, the PVC cannot be created.
spec.volumeName	Name of the PV object.	Yes	-	This parameter is mandatory when a PVC is created statically.
spec.storageClassName	Name of the StorageClass object.	Yes	-	When a PVC is created, an empty character string is transferred. If this parameter is not set, the default StorageClass object name will be used.