Create and use VolumePlacementStrategies

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Create your VolumePlacementStrategy along with your other storage resources:

Prerequisites

Portworx version: 2.1.2 and above

Construct a VolumePlacementStrategy spec

Create a YAML file containing the following common fields. All VolumePlacementStrategy CRDs use these fields:
- apiVersion as portworx.io/v1beta2
- kind as VolumePlacementStrategy
- metadata.name with the name of your strategy
Add any of the following affinity or antiaffinity sections to the spec:
This example adds a volumeAffinity rule to colocate Postgres volumes for performance:
```
  apiVersion: portworx.io/v1beta2
  kind: VolumePlacementStrategy
  metadata:
    name: postgres-volume-affinity
  spec:
    volumeAffinity:
      - matchExpressions:
        - key: app
          operator: In
          values:
            - postgres
```
Save and apply your spec with the kubectl apply command:
```
  kubectl apply -f yourVolumePlacementStrategy.yaml
```

Create other storage specs

Use a StorageClass

You can associate your VolumePlacementStrategy with a StorageClass and then reference that StorageClass in your PVC.

Create a StorageClass that references the VolumePlacementStrategy you created in the Construct a VolumePlacementStrategy spec steps above by specifying the placement_strategy parameter with the name of your VolumePlacementStrategy:
```
  apiVersion: storage.k8s.io/v1
  kind: StorageClass
  metadata:
    name: postgres-storage-class
  provisioner: kubernetes.io/portworx-volume
  parameters:
    placement_strategy: "postgres-volume-affinity"
```
Save and apply your StorageClass with the kubectl apply command:
```
  kubectl apply -f yourVolumePlacementStrategy.yaml
```

Create a PVC which references the StorageClass you created above, specifying the storageClass

  kind: PersistentVolumeClaim
  apiVersion: v1
  metadata:
     name: postgres-pvc
  spec:
     storageClassName: postgres-storage-class
     accessModes:
       - ReadWriteOnce
     resources:
       requests:
         storage: 2Gi

Save and apply your PVC with the kubectl apply command:
```
  kubectl apply -f yourPVC.yaml
```

Reference a VolumePlacementStrategy directly in a PVC

You can reference your VolumePlacementStrategy directly in your PVC using an annotation.

Create a PVC which references the VolumePlacementStrategy you created in the Construct a VolumePlacementStrategy spec steps above by specifying placement_strategy as an annotation with the name of your VolumePlacementStrategy:

  kind: PersistentVolumeClaim
    apiVersion: v1
    metadata:
      annotations: 
        placement_strategy: "postgres-volume-affinity"
      name: postgres-pvc
    spec:
      storageClassName: postgres-storage-class
      accessModes:
        - ReadWriteOnce
      resources:
        requests:
          storage: 2Gi

Save and apply your PVC with the kubectl apply command:
```
  kubectl apply -f yourPVC.yaml
```

Once you’ve applied your volumePlacementStrategy, StorageClass, and PVC, Portworx deploys volumes according to the rules you defined. Portworx also follows VolumePlacementStrategies when it restores volumes.

VolumePlacementStrategy CRD reference