Comment 3 for bug 1734636

Have found that without "enabled_backends" variable in cinder.conf we have the following worning from cinder:
LOG.warning(_LW('Configuration for cinder-volume does not specify '
                       '"enabled_backends", using DEFAULT as backend. '
                       'Support for DEFAULT section to configure drivers '
                       'will be removed in the next release.'))
And therefore we have the following output of "openstack volume show -f value -c os-vol-host-attr:host <volume_name>" command:
ctl01#DEFAULT
And "openstack volume service list"
+------------------+-----------+------+---------+-------+----------------------------+
| Binary | Host | Zone | Status | State | Updated At |
+------------------+-----------+------+---------+-------+----------------------------+
| cinder-scheduler | ctl03 | nova | enabled | up | 2017-12-11T11:50:36.000000 |
| cinder-scheduler | ctl01 | nova | enabled | up | 2017-12-11T11:50:39.000000 |
| cinder-scheduler | ctl02 | nova | enabled | up | 2017-12-11T11:50:36.000000 |
| cinder-volume | ctl03 | nova | enabled | up | 2017-12-11T11:46:44.000000 |
| cinder-volume | ctl01 | nova | enabled | up | 2017-12-11T11:46:44.000000 |
| cinder-volume | ctl02 | nova | enabled | up | 2017-12-11T11:46:45.000000 |
+------------------+-----------+------+---------+-------+----------------------------+
We have "volume_backend_name=DEFAULT" in cinder.conf
If we add "enabled_backends=lvm" to cinder conf (as it designed):
openstack volume service list
+------------------+-----------+------+---------+-------+----------------------------+
| Binary | Host | Zone | Status | State | Updated At |
+------------------+-----------+------+---------+-------+----------------------------+
| cinder-scheduler | ctl03 | nova | enabled | up | 2017-12-11T11:50:36.000000 |
| cinder-scheduler | ctl01 | nova | enabled | up | 2017-12-11T11:50:39.000000 |
| cinder-scheduler | ctl02 | nova | enabled | up | 2017-12-11T11:50:36.000000 |
| cinder-volume | ctl03 | nova | enabled | down | 2017-12-11T11:46:44.000000 |
| cinder-volume | ctl01 | nova | enabled | down | 2017-12-11T11:46:44.000000 |
| cinder-volume | ctl02 | nova | enabled | down | 2017-12-11T11:46:45.000000 |
| cinder-volume | ctl01@lvm | nova | enabled | up | 2017-12-11T11:50:32.000000 |
| cinder-volume | ctl02@lvm | nova | enabled | up | 2017-12-11T11:50:33.000000 |
| cinder-volume | ctl03@lvm | nova | enabled | up | 2017-12-11T11:50:34.000000 |
+------------------+-----------+------+---------+-------+----------------------------+
openstack volume show -f value -c os-vol-host-attr:host <volume_name>
ctl02@lvm#LVM
So it's true that right configured Cinder service shows host in the following format:
<host_name>@<backend>#<pool>