Hyper-convergence

When a pod runs on the same host as its volume, it is known as convergence or hyper-convergence. Because this configuration reduces the network overhead of an application, performance is typically better.

Using scheduler convergence

The recommended method to run your pods hyperconverged is to use STORK.

Once you have installed STORK, all you need to do is add schedulerName: stork in your application specs. STORK will then ensure that the nodes with data for a volume get prioritized when pods are being scheduled.

For example, this is how you would specify the scheduler name in a MySQL deployment:

apiVersion: apps/v1beta1
kind: Deployment
metadata:
  name: mysql
spec:
  strategy:
    rollingUpdate:
      maxSurge: 1
      maxUnavailable: 1
    type: RollingUpdate
  replicas: 1
  template:
    metadata:
      labels:
        app: mysql
        version: "1"
    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: mysql-data