The pods in K8s is ephemeral or transient which means they dont persist data and when pods get killed the data goes away with pods. To persist data we can attach the volume to the podssuch that the data processed by pods can store in volumes and even if the pods get killed te data persist.
Example1:
We can create a volume and volume needs storage
K8s supports
- NFS
- GlusterFS
- AWS EBS
- Flokcer
- Scaleio
- Azure Disk
- Google Persistent volume
The problem with Volumes is that we need to configure the volume details in pod definition files, every time changes needs to be made needs to be managed on all the pods everytime.
Persistent Volumes is the cluster wise pool of storage volumes and users can use that to be use by users using the persistent volume claims.
PVC are created by users to claimm the Persistent Volume. Once the PVC created K8s bind the PV to the pods. Every single PVC is bind to single PV. which meana that there is 1 to 1 mappping between PVC and PV. If there is no PV available the request will be in pending state.