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Local PV LVM VAC Parameters

Overview​

VolumeAttributesClass (VAC) parameters allow you to define Quality of Service (QoS) policies for Local PV LVM volumes.

These parameters control IOPS and bandwidth limits for filesystem and block-mode volumes provisioned through Local PV LVM. QoS policies are enforced at the node level using Linux cgroup v2 controls.

Supported VAC Parameters​

The following VAC parameters are supported for Local PV LVM volumes.

ParameterDescription
qosIopsLimitMaximum total IOPS limit
qosIopsReadLimitMaximum read IOPS limit
qosIopsWriteLimitMaximum write IOPS limit
qosBandwithPerSecMaximum total bandwidth per second
qosBandwithReadPerSecMaximum read bandwidth per second
qosBandwithWritePerSecMaximum write bandwidth per second

Example VAC Configuration

The following example configures total IOPS and bandwidth limits using a VAC.

apiVersion: storage.k8s.io/v1
kind: VolumeAttributesClass
metadata:
  name: lvm-qos-high
driverName: local.csi.openebs.io
parameters:
  qosIopsLimit: "50000"
  qosBandwithPerSec: "5000000"

Example Directional QoS Configuration

The following example configures separate read and write QoS limits.

apiVersion: storage.k8s.io/v1
kind: VolumeAttributesClass
metadata:
  name: lvm-qos-directional
driverName: local.csi.openebs.io
parameters:
  qosIopsReadLimit: "100"
  qosIopsWriteLimit: "200"
  qosBandwithReadPerSec: "7000Mi"
  qosBandwithWritePerSec: "8000Mi"

Update VAC QoS Parameters​

You can modify the QoS policy applied to a PVC by updating the volumeAttributesClassName field to reference a different VAC.

Example Updated VAC

apiVersion: storage.k8s.io/v1
kind: VolumeAttributesClass
metadata:
  name: lvm-qos-low
driverName: local.csi.openebs.io
parameters:
  qosIopsLimit: "20"
  qosBandwithPerSec: "20000"

Example Updated PVC

apiVersion: v1
kind: PersistentVolumeClaim
metadata:
  name: lvm-pvc
spec:
  accessModes:
    - ReadWriteOnce
  storageClassName: openebs-lvm
  volumeAttributesClassName: lvm-qos-low
  resources:
    requests:
      storage: 5Gi

Apply the updated PVC configuration:

kubectl apply -f pvc.yaml

After the PVC is updated, OpenEBS Local PV LVM automatically reconciles and applies the new QoS settings associated with the updated VolumeAttributesClass.

Invalid VAC Parameter Example​

Conflicting QoS Parameters

The following example uses conflicting QoS parameter values.

apiVersion: storage.k8s.io/v1
kind: VolumeAttributesClass
metadata:
  name: lvm-qos-conflict
driverName: local.csi.openebs.io
parameters:
  qosIopsLimit: "max"
  qosIopsReadLimit: "1000"

Verify VAC QoS Configuration​

Use the following command to verify the PVC configuration.

kubectl describe pvc <pvc-name>

Expected Results

  • The PVC references the updated VAC
  • Updated QoS parameters are applied to the Local PV LVM volume
  • QoS reconciliation completes automatically on supported Kubernetes versions

Support​

If you encounter issues or have a question, file a Github issue, or talk to us on the #openebs channel on the Kubernetes Slack server.

See Also​