Comment 1 for bug 1193113

The devstack volumes.sh exercise creates a volume and then issues 'nova volume-attach' to attach the volume to /dev/vdb.

http://logs.openstack.org/33478/1/gate/gate-tempest-devstack-vm-quantum/32609/console.html.gz

Somehow, /dev/vdb seems to be in the block_device.instance_block_mapping. In the screen-n-cpu.txt log, the instance has u'default_ephemeral_device': u'/dev/vdb' which looks related as the default_ephemeral_device does get returned as part of the mappings. If the requested device is found in the mappings, DevicePathInUse will be raised.

I'm not yet sure when/how default_ephemeral_device gets set. I looked at a recent gate run and didn't see it set to anything other than None.

http://logs.openstack.org/35361/15/gate/gate-tempest-devstack-vm-neutron/4343/logs/screen-n-cpu.txt.gz