Comment 4 for bug 1651370

> This results in two usable nodes, and a master with the scheduling disabled but which still has a 500GB volume attached to it, for no reason.

I meet this issue too.
As far as I know, when I specify docker_volume_size to 500, magnum will create two volume for cluster(1 master + 1 minion), one volume is attached to master, another volume is attached to minion.
Currently master is unscheduler, it is no need to attach volume to master.
So I need a patch to enhance 'docker_volume_size':
A: docker_volume_size just for minion, magnum just create volume for minion.
B: add master_docker_volume_size for master, add minion_docker_volume_size for minion, deprecate docker_volume_size.

A or B?

@strigazi
@flwang
any thoughts?