OKD allows use of VMware vSphere’s Virtual Machine Disk (VMDK) volumes. You can provision your OKD cluster with persistent storage using VMware vSphere. Some familiarity with Kubernetes and VMware vSphere is assumed.

VMware vSphere volumes can be provisioned dynamically. OKD creates the disk in vSphere and attaches this disk to the correct image.

The Kubernetes persistent volume framework allows administrators to provision a cluster with persistent storage and gives users a way to request those resources without having any knowledge of the underlying infrastructure.

PersistentVolumes are not bound to a single project or namespace; they can be shared across the OKD cluster. PersistentVolumeClaims are specific to a project or namespace and can be requested by users.

Additional references

Dynamically provisioning VMware vSphere volumes

Dynamically provisioning VMware vSphere volumes is the recommended method.

Prerequisites

  • An OKD cluster installed on a VMware vSphere version that meets the requirements for the components that you use. See Installing a cluster on vSphere for information about vSphere version support.

You can use either of the following procedures to dynamically provision these volumes using the default StorageClass.

Dynamically provisioning VMware vSphere volumes using the UI

OKD installs a default StorageClass, named thin, that uses the thin disk format for provisioning volumes.

Prerequisites
  • Storage must exist in the underlying infrastructure before it can be mounted as a volume in OKD.

Procedure
  1. In the OKD console, click StoragePersistent Volume Claims.

  2. In the persistent volume claims overview, click Create Persistent Volume Claim.

  3. Define the required options on the resulting page.

    1. Select the thin StorageClass.

    2. Enter a unique name for the storage claim.

    3. Select the access mode to determine the read and write access for the created storage claim.

    4. Define the size of the storage claim.

  4. Click Create to create the PersistentVolumeClaim and generate a PersistentVolume.

Dynamically provisioning VMware vSphere volumes using the CLI

OKD installs a default StorageClass, named thin, that uses the thin disk format for provisioning volumes.

Prerequisites
  • Storage must exist in the underlying infrastructure before it can be mounted as a volume in OKD.

Procedure (CLI)
  1. You can define a VMware vSphere PersistentVolumeClaim by creating a file, pvc.yaml, with the following contents:

    kind: PersistentVolumeClaim
    apiVersion: v1
    metadata:
      name: pvc (1)
    spec:
      accessModes:
      - ReadWriteOnce (2)
      resources:
        requests:
          storage: 1Gi (3)
    1 A unique name that represents the PersistentVolumeClaim.
    2 The PersistentVolumeClaim’s access mode. With ReadWriteOnce, the volume can be mounted with read and write permissions by a single node.
    3 The size of the PersistentVolumeClaim.
  2. Create the PersistentVolumeClaim from the file:

    $ oc create -f pvc.yaml

Statically provisioning VMware vSphere volumes

To statically provision VMware vSphere volumes you must create the virtual machine disks for reference by the persistent volume framework.

Prerequisites
  • Storage must exist in the underlying infrastructure before it can be mounted as a volume in OKD.

Procedure
  1. Create the virtual machine disks. Virtual machine disks (VMDKs) must be created manually before statically provisioning VMware vSphere volumes. Use either of the following methods:

    • Create using vmkfstools. Access ESX through Secure Shell (SSH) and then use following command to create a VMDK volume:

      $ vmkfstools -c <size> /vmfs/volumes/<datastore-name>/volumes/<disk-name>.vmdk
    • Create using vmware-diskmanager:

      $ shell vmware-vdiskmanager -c -t 0 -s <size> -a lsilogic <disk-name>.vmdk
  2. Create a PersistentVolume that references the VMDKs. Create a file, pv1.yaml, with the PersistentVolume object definition:

    apiVersion: v1
    kind: PersistentVolume
    metadata:
      name: pv1 (1)
    spec:
      capacity:
        storage: 1Gi (2)
      accessModes:
        - ReadWriteOnce
      persistentVolumeReclaimPolicy: Retain
      vsphereVolume: (3)
        volumePath: "[datastore1] volumes/myDisk"  (4)
        fsType: ext4  (5)
    1 The name of the volume. This name is how it is identified by PersistentVolumeClaims or Pods.
    2 The amount of storage allocated to this volume.
    3 The volume type used, with vsphereVolume for vSphere volumes. The label is used to mount a vSphere VMDK volume into Pods. The contents of a volume are preserved when it is unmounted. The volume type supports VMFS and VSAN datastore.
    4 The existing VMDK volume to use. If you used vmkfstools, you must enclose the datastore name in square brackets, [], in the volume definition, as shown previously.
    5 The file system type to mount. For example, ext4, xfs, or other file systems.

    Changing the value of the fsType parameter after the volume is formatted and provisioned can result in data loss and Pod failure.

  3. Create the PersistentVolume from the file:

    $ oc create -f pv1.yaml
  4. Create a PersistentVolumeClaim that maps to the PersistentVolume you created in the previous step. Create a file, pvc1.yaml, with the PersistentVolumeClaim object definition:

    apiVersion: v1
    kind: PersistentVolumeClaim
    metadata:
      name: pvc1 (1)
    spec:
      accessModes:
        - ReadWriteOnce (2)
      resources:
       requests:
         storage: "1Gi" (3)
      volumeName: pv1 (4)
    1 A unique name that represents the PersistentVolumeClaim.
    2 The PersistentVolumeClaim’s access mode. With ReadWriteOnce, the volume can be mounted with read and write permissions by a single node.
    3 The size of the PersistentVolumeClaim.
    4 The name of the existing PersistentVolume.
  5. Create the PersistentVolumeClaim from the file:

    $ oc create -f pvc1.yaml

Formatting VMware vSphere volumes

Before OKD mounts the volume and passes it to a container, it checks that the volume contains a file system that is specified by the fsType parameter value in the PersistentVolume (PV) definition. If the device is not formatted with the file system, all data from the device is erased, and the device is automatically formatted with the specified file system.

Because OKD formats them before the first use, you can use unformatted vSphere volumes as PVs.