The correct way to start a new container that shares the /data volume with the datastore container is to use the
--volumes-from flag. This flag mounts all the defined volumes from the referenced containers. In this case, the datastore container has a volume named /data, which is mounted in the service container at the same path.
The other options are incorrect because they either use invalid flags, such as --share-with or --volume- backend, or they create new volumes instead of sharing the existing one, such as -v datastore:/data or -v /data.
References:
* Docker Docs - Volumes
* Stack Overflow - How to map volume paths using Docker's --volumes-from?
* Docker Docs - docker run