Chapter 4. Configuring persistent storage

Procedure

1. In the OpenShift Container Platform web console, click Storage Persistent Volume Claims.
2. In the persistent volume claims overview, click Create Persistent Volume Claim.

3. Define the desired options on the page that appears.

   1. Select the previously-created storage class from the drop-down menu.
   2. Enter a unique name for the storage claim.
   3. Select the access mode. This selection determines the read and write access for the storage claim.
   4. Define the size of the storage claim.
4. Click Create to create the persistent volume claim and generate a persistent volume.

Procedure

1. Create a storage class:

   $ cat << EOF | oc create -f -
   apiVersion: storage.k8s.io/v1
   kind: StorageClass
   metadata:
     name: <storage-class-name> 

   1

   
   parameters:
     fsType: ext4 

   2

   
     encrypted: "true"
     kmsKeyId: keyvalue 

   3

   
   provisioner: ebs.csi.aws.com
   reclaimPolicy: Delete
   volumeBindingMode: WaitForFirstConsumer
   EOF

   Copy to Clipboard Toggle word wrap

   1

   Specifies the name of the storage class.

   2

   File system that is created on provisioned volumes.

   3

   Specifies the full Amazon Resource Name (ARN) of the key to use when encrypting the container-persistent volume. If you do not provide any key, but the encrypted field is set to true, then the default KMS key is used. See Finding the key ID and key ARN on AWS in the AWS documentation.

2. Create a persistent volume claim (PVC) with the storage class specifying the KMS key:

   $ cat << EOF | oc create -f -
   apiVersion: v1
   kind: PersistentVolumeClaim
   metadata:
     name: mypvc
   spec:
     accessModes:
       - ReadWriteOnce
     volumeMode: Filesystem
     storageClassName: <storage-class-name>
     resources:
       requests:
         storage: 1Gi
   EOF

   Copy to Clipboard Toggle word wrap

3. Create workload containers to consume the PVC:

   $ cat << EOF | oc create -f -
   kind: Pod
   metadata:
     name: mypod
   spec:
     containers:
       - name: httpd
         image: quay.io/centos7/httpd-24-centos7
         ports:
           - containerPort: 80
         volumeMounts:
           - mountPath: /mnt/storage
             name: data
     volumes:
       - name: data
         persistentVolumeClaim:
           claimName: mypvc
   EOF

   Copy to Clipboard Toggle word wrap

Procedure

1. In the OpenShift Container Platform web console, click Storage Storage Classes.
2. In the storage class overview, click Create Storage Class.

3. Define the desired options on the page that appears.

   1. Enter a name to reference the storage class.
   2. Enter an optional description.
   3. Select the reclaim policy.

   4. Select kubernetes.io/azure-disk from the drop down list.

      1. Enter the storage account type. This corresponds to your Azure storage account SKU tier. Valid options are Premium_LRS, PremiumV2_LRS, Standard_LRS, StandardSSD_LRS, and UltraSSD_LRS.

         Important

         The skuname PremiumV2_LRS is not supported in all regions, and in some supported regions, not all of the availability zones are supported. For more information, see Azure doc.

      2. Enter the kind of account. Valid options are shared, dedicated, and managed.

         Important

         Red Hat only supports the use of kind: Managed in the storage class.

         With Shared and Dedicated, Azure creates unmanaged disks, while OpenShift Container Platform creates a managed disk for machine OS (root) disks. But because Azure Disk does not allow the use of both managed and unmanaged disks on a node, unmanaged disks created with Shared or Dedicated cannot be attached to OpenShift Container Platform nodes.

   5. Enter additional parameters for the storage class as desired.
4. Click Create to create the storage class.

Procedure

1. In the OpenShift Container Platform web console, click Storage Persistent Volume Claims.
2. In the persistent volume claims overview, click Create Persistent Volume Claim.

3. Define the desired options on the page that appears.

   1. Select the previously-created storage class from the drop-down menu.
   2. Enter a unique name for the storage claim.
   3. Select the access mode. This selection determines the read and write access for the storage claim.
   4. Define the size of the storage claim.
4. Click Create to create the persistent volume claim and generate a persistent volume.

Procedure

1. Create a Secret object that contains the Azure File credentials:

   $ oc create secret generic <secret-name> --from-literal=azurestorageaccountname=<storage-account> \ 

   1

   
     --from-literal=azurestorageaccountkey=<storage-account-key> 

   2

   Copy to Clipboard Toggle word wrap

   1

   The Azure File storage account name.

   2

   The Azure File storage account key.

2. Create a PersistentVolume object that references the Secret object you created:

   apiVersion: "v1"
   kind: "PersistentVolume"
   metadata:
     name: "pv0001" 

   1

   
   spec:
     capacity:
       storage: "5Gi" 

   2

   
     accessModes:
       - "ReadWriteOnce"
     storageClassName: azure-file-sc
     azureFile:
       secretName: <secret-name> 

   3

   
       shareName: share-1 

   4

   
       readOnly: false

   Copy to Clipboard Toggle word wrap

   1

   The name of the persistent volume.

   2

   The size of this persistent volume.

   3

   The name of the secret that contains the Azure File share credentials.

   4

   The name of the Azure File share.

3. Create a PersistentVolumeClaim object that maps to the persistent volume you created:

   apiVersion: "v1"
   kind: "PersistentVolumeClaim"
   metadata:
     name: "claim1" 

   1

   
   spec:
     accessModes:
       - "ReadWriteOnce"
     resources:
       requests:
         storage: "5Gi" 

   2

   
     storageClassName: azure-file-sc 

   3

   
     volumeName: "pv0001" 

   4

   Copy to Clipboard Toggle word wrap

   1

   The name of the persistent volume claim.

   2

   The size of this persistent volume claim.

   3

   The name of the storage class that is used to provision the persistent volume. Specify the storage class used in the PersistentVolume definition.

   4

   The name of the existing PersistentVolume object that references the Azure File share.

1. Ensure that the executable file exists on all nodes in the cluster.
2. Place the executable file at the volume plugin path: /etc/kubernetes/kubelet-plugins/volume/exec/<vendor>~<driver>/<driver>.

Procedure

1. In the OpenShift Container Platform web console, click Storage Persistent Volume Claims.
2. In the persistent volume claims overview, click Create Persistent Volume Claim.

3. Define the desired options on the page that appears.

   1. Select the previously-created storage class from the drop-down menu.
   2. Enter a unique name for the storage claim.
   3. Select the access mode. This selection determines the read and write access for the storage claim.
   4. Define the size of the storage claim.
4. Click Create to create the persistent volume claim and generate a persistent volume.

Procedure

1. Create an object definition for the PV:

   apiVersion: v1
   kind: PersistentVolume
   metadata:
     name: pv0001 

   1

   
   spec:
     capacity:
       storage: 5Gi 

   2

   
     accessModes:
     - ReadWriteOnce 

   3

   
     nfs: 

   4

   
       path: /tmp 

   5

   
       server: 172.17.0.2 

   6

   
     persistentVolumeReclaimPolicy: Retain 

   7

   Copy to Clipboard Toggle word wrap

   1

   The name of the volume. This is the PV identity in various oc <command> pod commands.

   2

   The amount of storage allocated to this volume.

   3

   Though this appears to be related to controlling access to the volume, it is actually used similarly to labels and used to match a PVC to a PV. Currently, no access rules are enforced based on the accessModes.

   4

   The volume type being used, in this case the nfs plugin.

   5

   The path that is exported by the NFS server.

   6

   The hostname or IP address of the NFS server.

   7

   The reclaim policy for the PV. This defines what happens to a volume when released.

   Note

   Each NFS volume must be mountable by all schedulable nodes in the cluster.

2. Verify that the PV was created:

   $ oc get pv

   Copy to Clipboard Toggle word wrap

   Example output

   NAME     LABELS    CAPACITY     ACCESSMODES   STATUS      CLAIM  REASON    AGE
   pv0001   <none>    5Gi          RWO           Available                    31s

   Copy to Clipboard Toggle word wrap

3. Create a persistent volume claim that binds to the new PV:

   apiVersion: v1
   kind: PersistentVolumeClaim
   metadata:
     name: nfs-claim1
   spec:
     accessModes:
       - ReadWriteOnce 

   1

   
     resources:
       requests:
         storage: 5Gi 

   2

   
     volumeName: pv0001
     storageClassName: ""

   Copy to Clipboard Toggle word wrap

   1

   The access modes do not enforce security, but rather act as labels to match a PV to a PVC.

   2

   This claim looks for PVs offering 5Gi or greater capacity.

4. Verify that the persistent volume claim was created:

   $ oc get pvc

   Copy to Clipboard Toggle word wrap

   Example output

   NAME         STATUS   VOLUME   CAPACITY   ACCESS MODES   STORAGECLASS   AGE
   nfs-claim1   Bound    pv0001   5Gi        RWO                           2m

   Copy to Clipboard Toggle word wrap

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

     Copy to Clipboard Toggle word wrap

   • Create using vmware-diskmanager:

     $ shell vmware-vdiskmanager -c -t 0 -s <size> -a lsilogic <disk-name>.vmdk

     Copy to Clipboard Toggle word wrap

2. Create a persistent volume 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

   Copy to Clipboard Toggle word wrap

   1

   The name of the volume. This name is how it is identified by persistent volume claims 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.

   Important

   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 object from the file:

   $ oc create -f pv1.yaml

   Copy to Clipboard Toggle word wrap

4. Create a persistent volume claim that maps to the persistent volume 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

   Copy to Clipboard Toggle word wrap

   1

   A unique name that represents the persistent volume claim.

   2

   The access mode of the persistent volume claim. With ReadWriteOnce, the volume can be mounted with read and write permissions by a single node.

   3

   The size of the persistent volume claim.

   4

   The name of the existing persistent volume.

5. Create the PersistentVolumeClaim object from the file:

   $ oc create -f pvc1.yaml

   Copy to Clipboard Toggle word wrap