You will not find docker volumes, Each node has its own docker volumes under /var/lib/docker/volumes, it’ll be separate for nodes. To have them common you need to mount them via nfs or managed nfs. Best way to deploy new versions of custom app in self hosted docker setup - #13 by revant_one
Your database also need to be labeled and scheduled on same node everytime to access same volumes. Basically anything that has volume either need to be handled via nfs or lock it to same node.
Haven’t used multi-managers. Kubernetes can be re-thought if control-plane HA is needed.
I have achieved 1 manager, 2 worker,
NFS or Managed NFS for sites volume,
DBaaS or node locked stack or separate VM for DB.
Beyond that I’ll keep adding workers.
If I need anything more complex I’ll move to K8s.