State Persistence
State persistence in the context of Kubernetes/OpenShift refers to the ability to maintain and retain the state or data of applications even when they are stopped, restarted, or moved between nodes.
This is achieved through the use of volumes, persistent volumes (PVs), and persistent volume claims (PVCs). Volumes provide a way to store and access data in a container, while PVs serve as the underlying storage resources provisioned by the cluster. PVCs act as requests made by applications for specific storage resources from the available PVs. By utilizing PVs and PVCs, applications can ensure that their state is preserved and accessible across pod restarts and migrations, enabling reliable and consistent data storage and retrieval throughout the cluster.
Resources
References
apiVersion: v1
kind: PersistentVolumeClaim
metadata:
name: my-pvc
spec:
accessModes:
- ReadWriteOnce
resources:
requests:
storage: 1Gi
In this example, we define a PVC named my-pvc with the following specifications:
- accessModes specify that the volume can be mounted as read-write by a single node at a time ("ReadWriteOnce")
- resources.requests.storage specifies the requested storage size for the PVC ("1Gi")
Activities
| Task | Description | Link |
|---|---|---|
| Try It Yourself | ||
| Setting up Persistent Volumes | Create a Persistent Volume that's accessible from a SQL Pod. | Setting up Persistent Volumes |