Where does Kubernetes store data and state of containers managed through StatefulSet?

In Kubernetes, data and the state of containers managed through StatefulSet are stored in external storage connected to pods via PersistentVolume (PV) and PersistentVolumeClaim (PVC).

StatefulSet guarantees that each pod receives its own unique and stable volume for data storage, which persists regardless of the pod's lifecycle. These volumes are mounted into containers and ensure data persistence during restarts or pod recreations.

Thus, Kubernetes does not store data inside the containers or pods themselves (which are ephemeral), but uses PersistentVolumes, which can be implemented on various storage types (e.g., network disks, cloud storage, local disks, etc.).