Modify volume attributes of a PVC

A VolumeAttributesClass (VAC) lets you modify QoS limits and backend tags on an existing FlashArray block volume without cloning to a new StorageClass. This is useful when application requirements change and you need to adjust IOPS or bandwidth caps on a running PVC.

note

VolumeAttributesClass modification is supported only for FlashArray block volumes.

Prerequisites

Ensure that you are running:

• Kubernetes version 1.34 or later
• PX-CSI version 26.2.1 or later

How VolumeAttributesClass works

VolumeAttributesClass is a Kubernetes resource that defines a set of mutable parameters for PVCs. When you set spec.volumeAttributesClassName on a PVC, Kubernetes calls the CSI driver's ControllerModifyVolume RPC to apply the specified parameters to the underlying FlashArray volume.

During provisioning, parameters in the VolumeAttributesClass take precedence over matching parameters in the StorageClass. When you modify an existing PVC by referencing a VolumeAttributesClass, only the parameters defined in the VAC apply.

If the target backend does not support any parameter in the VolumeAttributesClass, the modification fails with an InvalidArgument error.

Apply a VolumeAttributesClass to a PVC

1. Create a VolumeAttributesClass manifest with the desired parameters. The following example sets QoS limits on a FlashArray block volume.

   apiVersion: storage.k8s.io/v1
   kind: VolumeAttributesClass
   metadata:
     name: fa-high-performance
   driverName: pxd.portworx.com
   parameters:
     max_iops: "50000"
     max_bandwidth: "2G"

2. Apply the manifest:

   kubectl apply -f vac.yaml

3. Patch the target PVC to reference the VolumeAttributesClass:

   kubectl patch pvc <pvc-name> -n <namespace> \
     --type=merge -p '{"spec":{"volumeAttributesClassName":"fa-high-performance"}}'

4. Verify that the modification completed by inspecting the PVC status:

   kubectl get pvc <pvc-name> -n <namespace> -o yaml

   When the modification is complete, status.currentVolumeAttributesClassName matches the name of the VolumeAttributesClass you applied.

Supported parameters

The following parameters are supported in a VolumeAttributesClass for FlashArray block volumes:

Parameter	Type	Description
max_iops	string	Sets a QoS IOPS cap. Range: 100 – 100,000,000. Example: "50000".
max_bandwidth	string	Sets a QoS bandwidth cap. Units: K, M, G. Example: "2G".
pure_backend_tags	string	Semicolon-separated tags to set on the volume. Format per tag: key:value or namespace:key:value. If you omit the namespace, it uses the default namespace. Example: "env:production;team:storage". Cannot modify the reserved portworx.internal:created-by tag.
pure_backend_remove_tags	string	Semicolon-separated tag keys to remove from the volume. Format per tag: key or namespace:key. If you omit the namespace, it uses the default namespace. Example: "env;team". Cannot remove the reserved portworx.internal:created-by tag.

For tag format details, see Add custom tags to FlashArray block volumes.