A service task container in a Swarm has access to the filesystem inherited from its Docker image. The data is made integral to a Docker container via its Docker image. At times, a Docker container may need to store or access data on a persistent filesystem. While a container has a filesystem, it is removed once the container exits. In order to store data across container restarts, that data must be persisted somewhere outside the container.
Data stored only within a container could result in the following issues:
The data is not persistent. The data is removed ...