Why do we think StatefulSets are broken? Well, if you run through the operational needs of a stateful workload in your head, there’s one key component that you might notice is missing:
What do you do when you need to resize the underlying disk?
The dataset is a common database store that typically grows at a pretty constant positive rate. Unless you support horizontal scaling and partitioning, you’ll need to add headroom in the disk as that dataset grows.
This is where Kubernetes falls flat on its face.