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Snapshot and Restore

See also the proposal of the functionality.

Getting Started

Prerequisites

You need to create a thin pool of LVM beforehand, because TopoLVM doesn't create one. For example:

lvcreate -T -n pool0 -L 4G myvg1

You also need to install the CRDs and the controller for volume snapshots. Please follow the official document to install them.

Set up a Device Class

Change your lvmd settings to use the thin pool you've created. For example, if you are using the Helm charts, modify your values.yaml as follows:

lvmd:
  deviceClasses:
    # ...
    # Other device classes are here.
    # ...
    - name: "thin"
      volume-group: "myvg1"
      type: thin
      thin-pool:
        name: "pool0"
        overprovision-ratio: 5.0

Set up a Storage Class

Create a storage class for the DeviceClass for the thin pool. For example, if you are using the Helm charts, modify your values.yaml as follows:

storageClasses:
  # ...
  # Other storage classes are here.
  # ...
  - name: topolvm-provisioner-thin
    storageClass:
      fsType: xfs
      isDefaultClass: false
      volumeBindingMode: WaitForFirstConsumer
      allowVolumeExpansion: true
      additionalParameters:
        '{{ include "topolvm.pluginName" . }}/device-class': "thin"

Deploy TopoLVM

Deploy TopoLVM with the settings you updated above. See also the Getting Started guide.

Run the following command to deploy my-pvc and my-pod, which use topolvm-provisioner-thin.

kubectl apply -f - <<EOF
kind: PersistentVolumeClaim
apiVersion: v1
metadata:
  name: my-pvc
spec:
  accessModes:
  - ReadWriteOnce
  resources:
    requests:
      storage: 1Gi
  storageClassName: topolvm-provisioner-thin
---
apiVersion: v1
kind: Pod
metadata:
  name: my-pod
spec:
  containers:
  - name: pause
    image: ubuntu:22.04
    command:
    - bash
    - -c
    - |
      sleep infinity
    volumeMounts:
    - mountPath: /data
      name: volume
  volumes:
  - name: volume
    persistentVolumeClaim:
      claimName: my-pvc
EOF

Write some data to the volume:

$ kubectl exec -it my-pod -- bash
root@my-pod:/# echo hello > /data/world
root@my-pod:/# ls /data/world
/data/world
root@my-pod:/# cat /data/world
hello

Take a Snapshot

Before taking snapshots, you need to prepare VolumeSnapshotClass as follows:

kubectl apply -f - <<EOF
apiVersion: snapshot.storage.k8s.io/v1
kind: VolumeSnapshotClass
metadata:
  name: topolvm-provisioner-thin
driver: topolvm.io
deletionPolicy: Delete
EOF

Then run the following command to take a snapshot:

kubectl apply -f - <<EOF
apiVersion: snapshot.storage.k8s.io/v1
kind: VolumeSnapshot
metadata:
  name: my-snapshot
spec:
  volumeSnapshotClassName: topolvm-provisioner-thin
  source:
    persistentVolumeClaimName: my-pvc
EOF

Restore a PV from the Snapshot

Run the following command to restore a PV from the snapshot taken above:

kubectl apply -f - <<EOF
kind: PersistentVolumeClaim
apiVersion: v1
metadata:
  name: my-pvc2
spec:
  accessModes:
  - ReadWriteOnce
  resources:
    requests:
      storage: 1Gi
  storageClassName: topolvm-provisioner-thin
  dataSource:
    name: my-snapshot
    kind: VolumeSnapshot
    apiGroup: snapshot.storage.k8s.io
---
apiVersion: v1
kind: Pod
metadata:
  name: my-pod2
spec:
  containers:
  - name: pause
    image: ubuntu:22.04
    command:
    - bash
    - -c
    - |
      sleep infinity
    volumeMounts:
    - mountPath: /data
      name: volume
  volumes:
  - name: volume
    persistentVolumeClaim:
      claimName: my-pvc2
EOF

And check the content of the volume:

$ kubectl exec -it my-pod2 -- cat /data/world
hello

See Also