VM Snapshot and Restore

VM snapshot allows you to snapshot the running VM with existing configuration and restore back to configuration point.

Snapshot a VM

Snapshotting a VM is supported for online and offline VMs.

When snapshotting a running VM the controller will check for the qemu guest agent in the VM. If the agent exists it will freeze the VM filesystems before taking the snapshot and unfreeze after the snapshot. It is recommended to take online snapshots with the guest agent for a better snapshot, if not present, a best effort snapshot will be taken.

Procedure

To enable snapshot functionality system does require snapshot CRD and snapshot controller to be created on system. Follow the steps below:

1. Run to install snapshot CRD and snapshot controller on Kubernets:

   • kubectl apply -f https://raw.githubusercontent.com/kubernetes-csi/external-snapshotter/master/client/config/crd/snapshot.storage.k8s.io_volumesnapshots.yaml

   • kubectl apply -f https://raw.githubusercontent.com/kubernetes-csi/external-snapshotter/master/client/config/crd/snapshot.storage.k8s.io_volumesnapshotcontents.yaml

   • kubectl apply -f https://raw.githubusercontent.com/kubernetes-csi/external-snapshotter/master/client/config/crd/snapshot.storage.k8s.io_volumesnapshotclasses.yaml

   • kubectl apply -f https://raw.githubusercontent.com/kubernetes-csi/external-snapshotter/master/deploy/kubernetes/snapshot-controller/rbac-snapshot-controller.yaml

   • kubectl apply -f https://raw.githubusercontent.com/kubernetes-csi/external-snapshotter/master/deploy/kubernetes/snapshot-controller/setup-snapshot-controller.yaml

2. Create VolumeSnapshotClass for cephfs and rbd:

    cat <<EOF>cephfs-storageclass.yaml
    —
    apiVersion: snapshot.storage.k8s.io/v1
    kind: VolumeSnapshotClass
    metadata:
      name: csi-cephfsplugin-snapclass
    driver: cephfs.csi.ceph.com
    parameters:
      clusterID: 60ee9439-6204-4b11-9b02-3f2c2f0a4344
      csi.storage.k8s.io/snapshotter-secret-name: ceph-pool-kube-cephfs-data
      csi.storage.k8s.io/snapshotter-secret-namespace: default
    deletionPolicy: Delete
    EOF
    cat <<EOF>rbd-storageclass.yaml
    —
    apiVersion: snapshot.storage.k8s.io/v1
    kind: VolumeSnapshotClass
    metadata:
      name: csi-rbdplugin-snapclass
    driver: rbd.csi.ceph.com
    parameters:
      clusterID: 60ee9439-6204-4b11-9b02-3f2c2f0a4344
      csi.storage.k8s.io/snapshotter-secret-name: ceph-pool-kube-rbd
      csi.storage.k8s.io/snapshotter-secret-namespace: default
    deletionPolicy: Delete
   EOF
   

   Note

   Get the cluster ID from: kubectl describe sc cephfs, rbd.

3. Create snapshot manifest of running VM using the example yaml below:

   cat<<EOF>cirros-snapshot.yaml
   apiVersion: snapshot.kubevirt.io/v1alpha1
   kind: VirtualMachineSnapshot
   metadata:
     name: snap-cirros
   spec:
     source:
       apiGroup: kubevirt.io
       kind: VirtualMachine
       name: pvc-test-vm
     failureDeadline: 3m
   EOF
   

4. Apply the snapshot manifest and verify if the snapshot is successfully created.

   kubectl apply -f cirros-snapshot.yaml
   [sysadmin@controller-0 kubevirt-GA-testing(keystone_admin)]$ kubectl get VirtualMachineSnapshot
   NAME          SOURCEKIND       SOURCENAME    PHASE       READYTOUSE   CREATIONTIME   ERROR
   snap-cirros   VirtualMachine   pvc-test-vm   Succeeded   true         28m
   

Example manifest to restore the snapshot:

<<EOF>cirros-restore.yaml
apiVersion: snapshot.kubevirt.io/v1alpha1
kind: VirtualMachineRestore
metadata:
  name: restore-cirros
spec:
  target:
    apiGroup: kubevirt.io
    kind: VirtualMachine
    name: pvc-test-vm
  virtualMachineSnapshotName: snap-cirros
EOF
kubectl apply -f cirros-restore.yaml

Verify the snapshot restore:

[sysadmin@controller-0 kubevirt-GA-testing(keystone_admin)]$ kubectl get VirtualMachineRestore
NAME               TARGETKIND       TARGETNAME    COMPLETE   RESTORETIME   ERROR
restore-cirros     VirtualMachine   pvc-test-vm   true       34m