Using Local Volumes without High Availability¶

With HwameiStor, you can run stateful applications very easily. This page takes a MySQL application as an example to use HwameiStor as its local storage.

Prerequisites¶

Hwameistor is installed successfully
StorageClass is created. If not, refer to Create StorageClass

After successful installation of HwameiStor, a StorageClass named hwameistor-storage-lvm-hdd will be installed by default in the Helm chart, and the StorageClass can be used to create local PVs.
1. Click Container Management to select a proper cluster to check its details. Click Container Storage to select StorageClass .
2. Click View YAML to see the details.
```
apiVersion: storage.k8s.io/v1
kind: StorageClass
metadata:
  name: hwameistor-storage-lvm-hdd
parameters:
  convertible: "false"
  csi.storage.k8s.io/fstype: xfs
  poolClass: HDD
  poolType: REGULAR
  replicaNumber: "1"
  striped: "true"
  volumeKind: LVM
provisioner: lvm.hwameistor.io
reclaimPolicy: Delete
volumeBindingMode: WaitForFirstConsumer
allowVolumeExpansion: true
```
  If the StorageClass fails to be created, you can Create StorageClass via UI or by using YAML. You can run the following command to apply YAML if it is ready:
```
kubectl apply -f examples/sc-local.yaml
```

Steps¶

Create StatefulSet via UI¶

Click Container Management to select a proper cluster and check the cluster details. Click Container Storage to select StatefulSets under Workloads and click Create By Image .
After completing the Basic Information , click Create PVC Template and configure the following parameters:
- Storage Classes: Local storage classes you have created.
- Capacity: The size of the local volume.
- Access Mode: It is recommended to use ReadWriteOnce.
- Container Path: The path where the data storage is mounted on the container.
Click OK , and click Next one by one to finish the creation wizard. After completion of the creation, click PVC to check whether the volume status is normal.

Create StatefulSet via YAML¶

Note

The following MySQL YAML file is from the Kubernetes website repository.

Once HwameiStor and StorageClass are ready, you can run the following command to create the MySQL container and its volume:

kubectl apply -f sts-mysql_local.yaml

Note that volumeClaimTemplates uses storageClassName: hwameistor-storage-lvm-hdd:

spec:
  volumeClaimTemplates:
  - metadata:
      name: data
      labels:
        app: sts-mysql-local
        app.kubernetes.io/name: sts-mysql-local
    spec:
      storageClassName: hwameistor-storage-lvm-hdd
      accessModes: ["ReadWriteOnce"]
      resources:
        requests:
          storage: 1Gi

and schedulerName: hwameistor-scheduler:

spec:
  template:
    spec:
      schedulerName: hwameistor-scheduler

View MySQL container and PVC/PV¶

In this example, the MySQL container is scheduled to node k8s-worker-3.

$ kubectl get po -l  app=sts-mysql-local -o wide
NAME                READY   STATUS    RESTARTS   AGE     IP            NODE        
sts-mysql-local-0   2/2     Running   0          3m08s   10.1.15.154   k8s-worker-3

$ kubectl get pvc -l  app=sts-mysql-local
NAME                     STATUS   VOLUME                                     CAPACITY   ACCESS MODES   STORAGECLASS                 AGE   VOLUMEMODE
data-sts-mysql-local-0   Bound    pvc-accf1ddd-6f47-4275-b520-dc317c90f80b   1Gi        RWO            hwameistor-storage-lvm-hdd    3m   Filesystem

View the `LocalVolume` object¶

By viewing LocalVolume(LV) with the same name as PV, you can see that the local volume is created on the node k8s-worker-3:

$ kubectl get lv pvc-accf1ddd-6f47-4275-b520-dc317c90f80b

NAME                                       POOL                   REPLICAS   CAPACITY     ACCESSIBILITY   STATE   RESOURCE   PUBLISHED      AGE
pvc-accf1ddd-6f47-4275-b520-dc317c90f80b   LocalStorage_PoolHDD   1          1073741824                   Ready   -1         k8s-worker-3    3m

[Optional] Scale the MySQL application into a three-node cluster¶

HwameiStor supports the horizontal autoscaling of StatefulSet. The StatefulSet will mount an independent local volume:

$ kubectl scale sts/sts-mysql-local --replicas=3

$ kubectl get po -l  app=sts-mysql-local -o wide
NAME                READY   STATUS     RESTARTS   AGE     IP            NODE        
sts-mysql-local-0   2/2     Running    0          4h38m   10.1.15.154   k8s-worker-3
sts-mysql-local-1   2/2     Running    0          19m     10.1.57.44    k8s-worker-2
sts-mysql-local-2   0/2     Init:0/2   0          14s     10.1.42.237   k8s-worker-1

$ kubectl get pvc -l  app=sts-mysql-local -o wide
NAME                     STATUS   VOLUME                                     CAPACITY   ACCESS MODES   STORAGECLASS                 AGE     VOLUMEMODE
data-sts-mysql-local-0   Bound    pvc-accf1ddd-6f47-4275-b520-dc317c90f80b   1Gi        RWO            hwameistor-storage-lvm-hdd   3m07s   Filesystem
data-sts-mysql-local-1   Bound    pvc-a4f8b067-9c1d-450f-aff4-5807d61f5d88   1Gi        RWO            hwameistor-storage-lvm-hdd   2m18s   Filesystem
data-sts-mysql-local-2   Bound    pvc-47ee308d-77da-40ec-b06e-4f51499520c1   1Gi        RWO            hwameistor-storage-lvm-hdd   2m18s   Filesystem

$ kubectl get lv
NAME                                       POOL                   REPLICAS   CAPACITY     ACCESSIBILITY   STATE   RESOURCE   PUBLISHED      AGE
pvc-47ee308d-77da-40ec-b06e-4f51499520c1   LocalStorage_PoolHDD   1          1073741824                   Ready   -1         k8s-worker-1   2m50s
pvc-a4f8b067-9c1d-450f-aff4-5807d61f5d88   LocalStorage_PoolHDD   1          1073741824                   Ready   -1         k8s-worker-2   2m50s
pvc-accf1ddd-6f47-4275-b520-dc317c90f80b   LocalStorage_PoolHDD   1          1073741824                   Ready   -1         k8s-worker-3   3m40s