Comment 5 for bug 1480504

Existing logic in the cinder charm causes it to exclude disks which are already mounted, via a check to charm-helper:is_device_mounted.

A recent charm-helpers fix resolved a bug where it was previously returning False even when a device was mounted (http://bazaar.launchpad.net/~charm-helpers/charm-helpers/devel/revision/409).

With that c-h fix, the cinder charm started getting an accurate device list for available (not-mounted) disk devices.

In the test environment, the 2nd disk (ephemeral) is already mounted @ /mnt, which is why cinder finds no devices available to use.