Anthos clusters on VMware is now Google Distributed Cloud (software only) for VMware. For more information, see the product overview.

Restore a volume from a snapshot

This document shows how to create a volume snapshot and then use the snapshot to restore the volume. The instructions here apply to clusters that use the vSphere CSI driver.

Before you begin

Read Using the vSphere Container Storage Interface driver.

Verify that your cluster has a StorageClass named standard-rwo and that the vSphere CSI driver is installed.

Your vSphere version, ESXi and vCenter Server, must be 7.0 Update 3 or later. For more information, see Troubleshooting storage.

Overview of steps

These are the primary steps of the exercise given in this document:

Create a PersistentVolumeClaim.

Create a PersistentVolumeClaim that requests the standard-rwo storage class. The cluster then dynamically provisions a PersistentVolume and associates it with your PersistentVolumeClaim.
Create a Deployment.

Create a Deployment that has one Pod. The Pod specifies a volume based on your PersistentVolumeClaim. The one container in the Pod mounts the volume at /hello/.
Write a file to the Pod volume.

Create a file named hello.txt in the Pod volume. The content of the file is "Hello World!".
Create a VolumeSnapshot.

Create a VolumeSnapshot that captures the state of the Pod volume.
Corrupt the file.

Alter the hello.txt file so that it looks like a corrupted file. The content of the file is now "Hello W-corrupted-file-orld!"
Use the snapshot to restore the volume.

Create a second PersistentVolumeClaim that uses your VolumeSnapshot as its data source. Edit your Deployment so that its volume is associated with the new PersistentVolumeClaim. Then verify that the hello.txt file has been restored.

Create a PersistentVolumeClaim

Here is a manifest for a PersistentVolumeClaim:

apiVersion: v1
kind: PersistentVolumeClaim
metadata:
  name: my-pvc
spec:
  accessModes:
    - ReadWriteOnce
  resources:
    requests:
      storage: 5Gi
  storageClassName: standard-rwo

In the preceding manifest, you can see that storageClassName is set to standard-rwo. This is the storage class associated with the vSphere CSI driver.

Save the manifest in a file named my-pvc.yaml. Create and view the PersistentVolumeClaim:

kubectl --kubeconfig CLUSTER_KUBECONFIG apply -f my-pvc.yaml

kubectl --kubeconfig CLUSTER_KUBECONFIG get pvc my-pvc

In the output, you can see that the PersistentVolumeClaim is bound to a dynamically provisioned PersistentVolume. For example, the following output shows that the PersistentVolumeClaim named my-pvc is bound to a PersistentVolume named pvc-467d211c-26e4-4d69-aaa5-42219aee6fd5:

my-pvc   Bound    pvc-467d211c-26e4-4d69-aaa5-42219aee6fd5  …  standard-rwo   100s

Create a Deployment

Here is a manifest for a Deployment:

apiVersion: apps/v1
kind: Deployment
metadata:
  name: my-deployment
spec:
  selector:
    matchLabels:
      app: hello-app
  template:
    metadata:
      labels:
        app: hello-app
    spec:
      containers:
      - name: hello-app
        image: google/cloud-sdk:slim
        args: [ "sleep", "3600" ]
        volumeMounts:
        - name: my-volume
          mountPath: /hello/
      volumes:
      - name: my-volume
        persistentVolumeClaim:
          claimName: my-pvc

In the context of this exercise, these are the important points to understand about the preceding Deployment manifest:

The Pod requests storage by specifying the PersistentVolumeClaim, my-pvc, that you created earlier.
The Pod has one container, and the container mounts the volume at /hello/.

Save the manifest in a file named my-deployment.yaml, and create the Deployment:

kubectl --kubeconfig CLUSTER_KUBECONFIG apply -f my-deployment.yaml

The Deployment has one Pod. Get the name of the Pod:

kubectl --kubeconfig CLUSTER_KUBECONFIG get pods

Make a note of the Pod name. For example, in the following output, the Pod name is my-deployment-7575c4f5bf-r59nt:

my-deployment-7575c4f5bf-r59nt   1/1     Running   0          65s

Create a file in the Pod volume, and view the file.

kubectl --kubeconfig CLUSTER_KUBECONFIG \
    exec POD_NAME \
    -- sh -c 'echo "Hello World!" > /hello/hello.txt'

kubectl --kubeconfig CLUSTER_KUBECONFIG \
    exec POD_NAME \
    -- sh -c 'cat /hello/hello.txt'

The output shows the content of the file /hello/hello.txt:

Hello World!

Create a snapshot

Here is a manifest for a VolumeSnapshot:

apiVersion: snapshot.storage.k8s.io/v1
kind: VolumeSnapshot
metadata:
  name: my-snapshot
spec:
  volumeSnapshotClassName: csi-vsphere-snapshot-class
  source:
    persistentVolumeClaimName: my-pvc

Save the manifest in a file named my-snapshot.yaml, and create the VolumeSnapshot:

kubectl --kubeconfig CLUSTER_KUBECONFIG apply -f my-snapshot.yaml

Corrupt the file in the volume

Change the content of the hello.txt so that it looks like it has been corrupted:

kubectl --kubeconfig CLUSTER_KUBECONFIG \
    exec POD_NAME \
    -- sh -c 'echo "Hello W-corrupted-file-orld!" > /hello/hello.txt'

kubectl --kubeconfig CLUSTER_KUBECONFIG \
    exec POD_NAME \
    -- sh -c 'cat /hello/hello.txt'

In the output, you can see that the file has been changed:

Hello W-corrupted-file-orld!

Restore

Here is a manifest for a second PersistentVolumeClaim:

apiVersion: v1
kind: PersistentVolumeClaim
metadata:
  name: my-pvc-2
spec:
  storageClassName: standard-rwo
  dataSource:
    name: my-snapshot
    kind: VolumeSnapshot
    apiGroup: snapshot.storage.k8s.io
  accessModes:
    - ReadWriteOnce
  resources:
    requests:
      storage: 5Gi

In the preceding manifest, you can see that the data source for the new PersistentVolume claim is the VolumeSnapshot that you created previously.

Save the manifest in a file named my-pvc-2.yaml. Create and view the PersistentVolumeClaim:

kubectl --kubeconfig CLUSTER_KUBECONFIG apply -f my-pvc-2.yaml

kubectl --kubeconfig CLUSTER_KUBECONFIG get pvc my-pvc-2

Open the Deployment for editing:

kubectl --kubeconfig CLUSTER_KUBECONFIG edit deployment my-deployment

Change my-pvc to my-pvc-2, and close the editor:

…
  volumes:
  - name: my-volume
    persistentVolumeClaim:
    claimName: my-pvc-2

The Deployment deletes the Pod, and creates a new Pod that uses the new PersistentVolumeClaim.

Wait a few minutes, and then get the new Pod name:

kubectl --kubeconfig CLUSTER_KUBECONFIG get pods

Verify that the Pod volume has been restored:

kubectl --kubeconfig CLUSTER_KUBECONFIG \
   exec NEW_POD_NAME \
   -- sh -c 'cat /hello/hello.txt'

The output shows that the volume has been restored:

Hello World!

Troubleshooting

For troubleshooting guidance, see Troubleshooting storage.