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
• When the application Pod applies for multiple data volume PVC, the proper 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)

Steps on UI¶

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.

   

5. Create migration task

   Go to the proper cluster → Click the left Container Storage → Hwameistor Enter the Hwameistor interface, select the locally unbound volume, The proper 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.

   

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

Oneline trial 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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