I know about snapshots and tested volume cloning. And it works, when storage class is the same.
But what if I have two storage classes: one for fast ssd and second for cold storage hdd over network and I want periodically make backup to cold storage? How to do it?
This is not a thing Kubernetes supports since it would be entirely up to your underlying storage. The simple version would be a pod that mounts both and runs rsync I guess?