Create and use Volume Placement Strategies in OCP on bare metal

Create your VolumePlacementStrategy along with your other storage resources:

Prerequisites

• Portworx version: 2.1.2 and above

Construct a VolumePlacementStrategy spec

1. 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:

   • replicaAffinity
   • replicaAntiAffinity
   • volumeAffinity
   • volumeAntiAffinity

   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

2. Save and apply your spec with the oc apply command:

   oc 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.

1. 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: pxd.portworx.com
   parameters:
     placement_strategy: "postgres-volume-affinity"

2. Save and apply your StorageClass with the oc apply command:

   oc apply -f yourVolumePlacementStrategy.yaml

3. 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

4. Save and apply your PVC with the oc apply command:

   oc apply -f yourPVC.yaml

Reference a VolumePlacementStrategy directly in a PVC

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

1. 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

2. Save and apply your PVC with the oc apply command:

   oc 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.