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Volume Expansion

HwameiStor supports CSI Volume Expansion. This feature enables online expansion of volumes by modifying the size of PVC. Currently, it supports both manual and automatic expansion methods.

Manual Expansion

  1. Access the proper cluster and navigate to Container Storage -> HwameiStor

  2. Click Local Volumes . On the right side of the local volume list, click ┇ and select Expand .

    expand01

  3. In the Expand dialog box, enter the new size for expansion. In this example, expand from 1G to 10G, then click OK .

    expand02

  4. Refresh the current list and check that the capacity of the current local volume has changed from 1G to 10G.

    expand03

Automatic Expansion

The component hwameistor-pvc-autoresizer provides the capability for automatic PVC expansion. The expansion behavior is controlled by the ResizePolicy CRD.

ResizePolicy

Below is an example CR:

apiVersion: hwameistor.io/v1alpha1
kind: ResizePolicy
metadata:
  name: resizepolicy1
spec:
  warningThreshold: 60
  resizeThreshold: 80
  nodePoolUsageLimit: 90

The three int-type fields warningThreshold, resizeThreshold, and nodePoolUsageLimit represent percentages.

  • warningThreshold is currently not associated with any alert action. It serves as a target ratio, meaning that after expansion, the volume usage will be below this percentage.
  • resizeThreshold indicates a usage ratio. When the volume usage reaches this percentage, the expansion action will be triggered.
  • nodePoolUsageLimit represents the upper limit of node StorageClass usage. If the usage of a StorageClass reaches this percentage, the volumes in this StorageClass will not be automatically expanded.

Matching Rules

This is an example CR with a label-selector.

apiVersion: hwameistor.io/v1alpha1
kind: ResizePolicy
metadata:
  name: example-policy
spec:
  warningThreshold: 60
  resizeThreshold: 80
  nodePoolUsageLimit: 90
  storageClassSelector:
    matchLabels:
      pvc-resize: auto
  namespaceSelector:
    matchLabels:
      pvc-resize: auto
  pvcSelector:
    matchLabels:
      pvc-resize: auto

ResizePolicy has three label-selectors:

  • pvcSelector indicates that the PVCs selected by this selector will be automatically expanded according to the policy.
  • namespaceSelector indicates that the PVCs in the namespaces selected by this selector will be automatically expanded according to the policy.
  • storageClassSelector indicates that the PVCs created from the StorageClass selected by this selector will be automatically expanded according to the policy.

These three selectors have an "AND" relationship. If you specify multiple selectors in a ResizePolicy, only the PVCs that meet all the selectors will match the policy. If no selector is specified in the ResizePolicy, it becomes a cluster-wide ResizePolicy, acting as the default policy for all PVCs in the cluster.

FAQs

How to Watch the Expansion Process

The more capacity added, the longer the expansion time required. You can watch the entire expansion process in the PVC event logs.

kubectl describe pvc data-sts-mysql-local-0

Events:
  Type     Reason                      Age                From                                Message
  ----     ------                      ----               ----                                -------
  Warning  ExternalExpanding           34s                volume_expand                       Ignoring the PVC: didn't find a plugin capable of expanding the volume; waiting for an external controller to process this PVC.
  Warning  VolumeResizeFailed          33s                external-resizer lvm.hwameistor.io  resize volume "pvc-b9fc8651-97b8-414c-8bcf-c8d2708c4ee8" by resizer "lvm.hwameistor.io" failed: rpc error: code = Unknown desc = volume expansion not completed yet
  Normal   Resizing                    32s (x2 over 33s)  external-resizer lvm.hwameistor.io  External resizer is resizing volume pvc-b9fc8651-97b8-414c-8bcf-c8d2708c4ee8
  Normal   FileSystemResizeRequired    32s                external-resizer lvm.hwameistor.io  Require file system resize of volume on node
  Normal   FileSystemResizeSuccessful  11s                kubelet                             MountVolume.NodeExpandVolume succeeded for volume "pvc-b9fc8651-97b8-414c-8bcf-c8d2708c4ee8" k8s-worker-3

How to Watch the Expanded PVC/PV

kubectl get pvc data-sts-mysql-local-0

NAME                     STATUS   VOLUME                                     CAPACITY   ACCESS MODES   STORAGECLASS                 AGE
data-sts-mysql-local-0   Bound    pvc-b9fc8651-97b8-414c-8bcf-c8d2708c4ee8   2Gi        RWO            hwameistor-storage-lvm-hdd   96m

kubectl get pv pvc-b9fc8651-97b8-414c-8bcf-c8d2708c4ee8

NAME                                       CAPACITY   ACCESS MODES   RECLAIM POLICY   STATUS   CLAIM                            STORAGECLASS                 REASON   AGE
pvc-b9fc8651-97b8-414c-8bcf-c8d2708c4ee8   2Gi        RWO            Delete           Bound    default/data-sts-mysql-local-0   hwameistor-storage-lvm-hdd            96m

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