So far, we have discussed storage solutions that store data outside the Kubernetes cluster (except for emptyDir and HostPath, which are not persistent). Flocker is a little different. It is Docker-aware. It was designed to let Docker data volumes transfer with their container when the container is moved between nodes. You may want to use the Flocker volume plugin if you're migrating a Docker-based system that use a different orchestration platform, such as Docker compose or Mesos, to Kubernetes, and you use Flocker for orchestrating storage. Personally, I feel that there is a lot of duplication between what Flocker does and what Kubernetes does to abstract storage.

Flocker has a control service and agents on each node. Its architecture is very similar to Kubernetes with its API server and Kubelet running on each node. The...