In this section, we will understand the Kubernetes storage conceptual model and see how to map persistent storage into containers so they can read and write. Let's start by understanding the problem of storage. Containers and pods are ephemeral. Anything a container writes to its own filesystem gets wiped out when the container dies. Containers can also mount directories from their host node and read or write. That will survive container restarts, but the nodes themselves are not immortal.
There are other problems, such as ownership for mounted hosted directories when the container dies. Just imagine a bunch of containers writing important data to various data directories on their host and then go away leaving all that data all over the nodes with no direct way to tell what container wrote what data. You can try to record this information, but where would you record it? It's pretty clear that for a large-scale system, you need persistent storage accessible...