I add change the --driver and --dirver-opts option into yaml or json profile to start daemon. The same time, the profile can create different pool-type (I rename "storagetype") to create volume. Different pool-type can link to different backend (I just finish the devmapper). When the user create volume, he can specify pool by "--storagetype". Different storagetype has own cfg file and store in different file folder.
I also add option of "convoy list-type" to list current storagetype.