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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.

ParameterDescriptionAccepted Values
qosIopsLimitMaximum Read/Write IOPS limitNon-zero positive integer or max
qosIopsReadLimitMaximum read IOPS limitNon-zero positive integer or max
qosIopsWriteLimitMaximum write IOPS limitNon-zero positive integer or max
qosBandwithPerSecMaximum Read/Write bandwidth per secondNon-zero positive integer (bytes/sec) or supported size suffixes such as 7000Mi
qosBandwithReadPerSecMaximum read bandwidth per secondNon-zero positive integer (bytes/sec) or supported size suffixes such as 7000Mi
qosBandwithWritePerSecMaximum write bandwidth per secondNon-zero positive integer (bytes/sec) or supported size suffixes such as 7000Mi
note

Setting an IOPS parameter to max disables IOPS limiting for that parameter on the volume. A value of 0 is not supported for IOPS or bandwidth parameters.

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​