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Volume Migration

Migrate is an important operation and maintenance management feature in HwameiStor. When the copy of the node where the data volume bound to the application is located is damaged, the copy of the volume can be migrated to other nodes, and the application will be rescheduled after successfully migrating to the new node, and bound the data volume.

Basic concept

LocalVolumeGroup(LVG) (data volume group) management is an important feature in HwameiStor. When the application Pod applies for multiple data volumes PVC, in order to ensure the correct operation of the Pod, these data volumes must have certain attributes, such as: the number of copies of the data volume, and the node where the copies are located. It is a very important capability in HwameiStor to correctly manage these associated data volumes through the data volume group management function.

Prerequisites

LVG needs to be deployed in the Kubernetes system, and the deployment application needs to meet the following conditions:

  • Support for lvm type volumes
  • convertible type volume (need to add ConfigMap convertible: true in sc)
    • When the application Pod applies for multiple data volume PVC, the corresponding data volumes need to use the same configuration sc
    • When migrating based on LocalVolume granularity, data volumes belonging to the same LocalVolumeGroup will not be migrated together by default (if they are migrated together, you need to configure the switch MigrateAllVols: true)

Interface steps

  1. Create convertible StorageClass

    Install through the interface, please refer to How to Create StorageClass

  2. Create multiple PVC

    Create multiple PVC through the interface, please refer to How to Create PVC

  3. Deploy Pod with multiple volumes

    Create applications through the interface, please refer to How to Create Workloads, and mount the two created PVCs.

  4. Unbound Pod with multiple volumes

    Before migration, please unbound PVC. You can unbound them by Editing Workloads.

    unbound01

  5. Create migration task

    Go to the corresponding cluster → Click the left Container Storage → Hwameistor Enter the Hwameistor interface, select the locally unbound volume, The corresponding PVCs are pvc-test01 and pvc-test02. Click ... and select Migrate, choose the SourceNode and TargetNode.

    SourceNode: The node where the local volume replica is located.

    TargetNode: After specifying, the original replica will be migrated to the target node. If Auto is chosen, the local volume replica will be automatically scheduled to other nodes.

    If two/multiple local volumes are bounded on the same application, the two volumes will automatically form a local volume group for migration.

    migration01

  6. Click the corresponding local volume to enter the details and check the migration status.

Oneline trail steps

  1. Create convertible StorageClass

    cd ../../deploy/
kubectl apply -f storageclass-convertible-lvm.yaml

  2. Create multiple PVC

    kubectl apply -f pvc-multiple-lvm.yaml

  3. Deploy the multi-volume Pod

    kubectl apply -f nginx-multiple-lvm.yaml

  4. Unbound the multi-volume Pod

    kubectl patch deployment nginx-local-storage-lvm --patch '{"spec": {"replicas": 0}}' -n hwameistor

  5. Create the migration task

    cat > ./migrate_lv.yaml <<- EOF
apiVersion: hwameistor.io/v1alpha1
kind: LocalVolumeMigrate
metadata:
  namespace: hwameistor
  name: <localVolumeMigrateName>
spec:
sourceNode: <sourceNodeName>
  targetNodesSuggested: 
  - <targetNodesName1>
  - <targetNodesName2>
  volumeName: <volName>
  migrateAllVols: <true/false>
EOF

    kubectl apply -f ./migrate_lv.yaml

  6. View migration status

    kubectl get LocalVolumeMigrate  -o yaml

    apiVersion: v1
items:
- apiVersion: hwameistor.io/v1alpha1
  kind: LocalVolumeMigrate
  metadata:
  annotations:
  kubectl.kubernetes.io/last-applied-configuration: |
  {"apiVersion":"hwameistor.io/v1alpha1","kind":"LocalVolumeMigrate","metadata":{"annotations":{},"name":"localvolumemigrate-1","namespace":"hwameistor"},"spec":{"migrateAllVols":true,"sourceNodesNames":["dce-172-30-40-61"],"targetNodesNames":["172-30-45-223"],"volumeName":"pvc-1a0913ac-32b9-46fe-8258-39b4e3b696a4"}}
  creationTimestamp: "2022-07-07T12:34:31Z"
  generation: 1
  name: localvolumemigrate-1
  namespace: hwameistor
  resourceVersion: "12828637"
  uid: 78af7f1b-d701-4b03-84de-27fafca58764
  spec:
  abort: false
  migrateAllVols: true
  sourceNodesNames:
  - dce-172-30-40-61
    targetNodesNames:
  - 172-30-45-223
    volumeName: pvc-1a0913ac-32b9-46fe-8258-39b4e3b696a4
    status:
    replicaNumber: 1
    state: InProgress
    kind: List
    metadata:
    resourceVersion: ""
    selfLink: ""

  7. View migration success status

    [root@172-30-45-222 deploy]# kubectl get lvr

    NAME                                              CAPACITY     NODE            STATE   SYNCED   DEVICE                                                                  AGE
pvc-1a0913ac-32b9-46fe-8258-39b4e3b696a4-9cdkkn   1073741824   172-30-45-223   Ready   true     /dev/LocalStorage_PoolHDD-HA/pvc-1a0913ac-32b9-46fe-8258-39b4e3b696a4   77s
pvc-d9d3ae9f-64af-44de-baad-4c69b9e0744a-7ppmrx   1073741824   172-30-45-223   Ready   true     /dev/LocalStorage_PoolHDD-HA/pvc-d9d3ae9f-64af-44de-baad-4c69b9e0744a   77s

  8. After successful migration, rebound the data volume Pod

    kubectl patch deployment nginx-local-storage-lvm --patch '{"spec": {"replicas": 1}}' -n hwameistor

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