In this section, you will fix the issue we experienced earlier in this chapter of non-persistent storage if a node goes down. Before we start, let's make sure that the cluster is in a clean state:

ab443838-9b3e-4811-b287-74e417a9@Azure:~$ kc get all
NAME                 TYPE        CLUSTER-IP   EXTERNAL-IP   PORT(S)   AGE
service/kubernetes   ClusterIP   10.0.0.1     <none>        443/TCP   4d

Get the status of running nodes:

ab443838-9b3e-4811-b287-74e417a9@Azure:~$ kc get nodes
NAME                       STATUS    ROLES     AGE       VERSION
aks-agentpool-18162866-0   Ready     agent     4d        v1.11.5
aks-agentpool-18162866-1   Ready     agent     3d        v1.11.5

In the last example, we saw that the messages stored in redis-master were lost if it gets restarted. The reason for this is that redis-master stores all data in its container, and whenever it is restarted, it uses the clean image without the data. In order to survive reboots, the data has to be stored outside. Kubernetes uses PVCs to abstract the underlying storage provider to provide this external storage.