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PVC Autoresizing

The component "hwameistor-pvc-autoresizer" provides the ability to automatically resize Persistent Volume Claims (PVCs). The resizing behavior is controlled by the ResizePolicy custom resource definition (CRD).

ResizePolicy​

An example of CR is as below:

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

The three fields warningThreshold, resizeThreshold, and nodePoolUsageLimit are all of type integer and represent percentages.

  • warningThreshold currently does not have any associated alert actions. It serves as a target ratio, indicating that the usage rate of the volume will be below this percentage after resizing is completed.
  • resizeThreshold indicates a usage rate at which the resizing action will be triggered when the volume's usage rate reaches this percentage.
  • nodePoolUsageLimit represents the upper limit of storage pool usage on a node. If the usage rate of a pool reaches this percentage, volumes assigned to that pool will not automatically resize.

Match Rules​

This is an examle of CR with label selectors.

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

The ResizePolicy has three label selectors:

  • pvcSelector indicates that PVCs selected by this selector will automatically resize according to the policy that selected them.
  • namespaceSelector indicates that PVCs under namespaces selected by this selector will automatically resize according to this policy.
  • storageClassSelector indicates that PVCs created from storage classes selected by this selector will automatically resize according to this policy.

These three selectors have an "AND" relationship. If you specify multiple selectors in a ResizePolicy, the PVCs must match all of the selectors in order to be associated with that policy. If no selectors are specified in the ResizePolicy, it becomes a cluster-wide ResizePolicy, acting as the default policy for all PVCs in the entire cluster.