Create PX-Fast PVCs


PX-Fast is a Portworx feature that enables an accelerated IO path for the volumes that meet certain prerequisites. It is optimized for workloads requiring consistent low latencies. PX-Fast is built on top of a Portworx PX-StoreV2 datastore.

NOTE:

  • PX-Fast requires a special license for the functionality to be active. Contact Portworx support team for obtaining this license.

  • PX-Fast works only if Portworx is installed with PX-StoreV2 datastore.

Prerequisites

You must have deployed Portworx with PX-StoreV2 datastore.

Create PX-Fast PVCs

Perform the following steps to create PX-Fast volumes.

Create a StorageClass

  1. Save the following as a YAML file:

    kind: StorageClass
    apiVersion: storage.k8s.io/v1
    metadata:
        name: px-fast
    provisioner: kubernetes.io/portworx-volume
    parameters:
        repl: "1"
        fastpath: "true"
    allowVolumeExpansion: true

    Note that this StorageClass will have 1 replica, and the Portworx volumes referring to this StorageClass will also have 1 replica.

  2. Run the following kubectl apply command to create a StorageClass:

    kubectl apply -f <px-fast>.yaml
    storageclass.storage.k8s.io/px-fast-sc created
  3. Verify that the StorageClass is created:

    kubectl describe storageclass px-fast-sc
    Provisioner:           kubernetes.io/portworx-volume
    Parameters:            fastpath=true,repl=1
    AllowVolumeExpansion:  <unset>
    MountOptions:          <none>
    ReclaimPolicy:         Delete
    VolumeBindingMode:     Immediate
    Events:                <none>

Create a PVC

  1. Save the following as YAML file:

    kind: PersistentVolumeClaim
    apiVersion: v1
    metadata:
        name: px-fast-pvc
    spec:
        storageClassName: px-fast
        accessModes:
            - ReadWriteOnce
        resources:
            requests:
                storage: 1Gi
  2. Run the following kubectl apply command to create a PX-Fast PVC:

    kubectl apply -f <px-pvc>.yaml
  3. Verify that a persistent volume claim is created:

    kubectl get pvc

Deploy an application using a PX-Fast PVC

To utilize PX-Fast on the above PVCs, the application pods must run on the same node where the volume replica exists. The following sample deployment spec uses the stork.libopenstorage.org/preferLocalNodeOnly: "true" annotation, which enforces the pod to be scheduled on the node where the volume replica exists:

apiVersion: apps/v1
kind: Deployment
metadata:
  name: mysql
spec:
  selector:
    matchLabels:
      app: mysql
  strategy:
    rollingUpdate:
      maxSurge: 1
      maxUnavailable: 1
    type: RollingUpdate
  replicas: 1
  template:
    metadata:
      annotations:
        stork.libopenstorage.org/preferLocalNodeOnly: "true"
      labels:
        app: mysql
    spec:
      schedulerName: stork
      containers:
      - image: mysql:5.6
        name: mysql
        env:
        - name: MYSQL_ROOT_PASSWORD
          value: password
        ports:
        - containerPort: 3306
        volumeMounts:
        - name: mysql-persistent-storage
          mountPath: /var/lib/mysql
      volumes:
      - name: mysql-persistent-storage
        persistentVolumeClaim:
          claimName: px-fast-pvc

Note that the schedulerNamefield in the above spec is set to stork. From Stork version 2.9.0 or newer, the schedulerName is set to stork by default.

The annotation stork.libopenstorage.org/preferLocalNodeOnly: "true" enforces the pod to be scheduled on the node where the volume replica exists. To avoid this enforced behavior, you can choose not to specify the stork.libopenstorage.org/preferLocalNodeOnly: true annotation. In such a case, Stork will do best-effort to place the application pod on the node where the replica exists, but if the application pod gets attached to a non-replica node, it cannot use PX-Fast.

NOTE: PX-Fast is not supported for PVCs with more than 1 replica. It is also not supported on the aggregated volumes.

Reference

PX-Fast volumes using pxctl


Last edited: Friday, Oct 28, 2022