After setting up a data container using the following command:docker create -v /data --name datastore...

 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