Before someone else is googling his/hers ass off.

Cinder is able to create multi-attach able disks but nova has the feature not implemented yet. It seems to be targeted for version 14.

I recognized this behavior as i tried to connect OpenShift to OpenStack and dynamically provision storage.

Links are:

https://bugzilla.redhat.com/show_bug.cgi?id=1033185

https://bugzilla.redhat.com/show_bug.cgi?id=1033180

https://access.redhat.com/solutions/2429871

https://access.redhat.com/solutions/2529261