Convoy is a Docker volume plugin for a variety of storage back-ends. It's designed to be a simple Docker volume plug-ins that supports vendor-specific extensions such as snapshots, backups and restore. It's written in Go and can be deployed as a standalone binary.Docker has various drivers(aufs, device mapper, etc) for container's root image, but not for volumes. User can create volume through docker run -v volname, but it's disposable, cannot be easily reused for new containers or containers on the other hosts. For example, if you start a wordpress container with database, add some posts, remove the container, then the modified database would lost.