Shared image storage between nodes


While I have a vast knowledge about “traditional” virtualisation and convergence, I’m pretty new to docker and I love rancher cause its bringing simplicity to something I find a pretty over-complicated technology.

However, maybe someone can help me to understand and or bridge something I’m missing.

I’ve build an environment with 4 nodes (one is my rancher server + 3 nodes with docker.).
Installing a stack (wordpress for example) pulls the images somewhere on the node group.and creates a local cow storage for the data of the container on a local node where its running.

But once for example turning off that node the stack starts somewhere else by downloading the images and brings me a fresh new WordPress that needs to be installed.

In a converged world I would have some ceph or gluster that shares on all nodes the storage data and brings up my container with the same data everywhere.

For what do i need to look for to have something similar in Rancher (docker)

Thanks for giving me some starting points.