There are differences in how '--container' parameter is interpreted by different cinder backup drivers.
- swift creates a bucket, nfs creates a directory, and ceph uses it as a pool name to override backup_ceph_pool.
- For ceph if the pool does not exists the backup creation eventually fails with
~~~
2020-05-27 00:22:20.902 1 DEBUG os_brick.initiator.connectors.rbd [req-f8a7f99b-2986-4893-a6aa-a2a778f9d179 ed47f67e4b9b494dae754c0938b1845d 0b6b14498ca740779af8258b452cc9d5 - default default] <== disconnect_volume: return (4ms) None trace_logging_wrapper /usr/lib/python2.7/site-packages/os_brick/utils.py:170
2020-05-27 00:22:21.025 1 ERROR oslo_messaging.rpc.server [req-f8a7f99b-2986-4893-a6aa-a2a778f9d179 ed47f67e4b9b494dae754c0938b1845d 0b6b14498ca740779af8258b452cc9d5 - default default] Exception during message handling: ObjectNotFound: [errno 2] error opening pool 'new_ceph_pool'
2020-05-27 00:22:21.025 1 ERROR oslo_messaging.rpc.server Traceback (most recent call last):
2020-05-27 00:22:21.025 1 ERROR oslo_messaging.rpc.server File "/usr/lib/python2.7/site-packages/oslo_messaging/rpc/server.py", line 163, in _process_incoming
2020-05-27 00:22:21.025 1 ERROR oslo_messaging.rpc.server res = self.dispatcher.dispatch(message)
2020-05-27 00:22:21.025 1 ERROR oslo_messaging.rpc.server File "/usr/lib/python2.7/site-packages/oslo_messaging/rpc/dispatcher.py", line 220, in dispatch
2020-05-27 00:22:21.025 1 ERROR oslo_messaging.rpc.server return self._do_dispatch(endpoint, method, ctxt, args)
2020-05-27 00:22:21.025 1 ERROR oslo_messaging.rpc.server File "/usr/lib/python2.7/site-packages/oslo_messaging/rpc/dispatcher.py", line 190, in _do_dispatch
2020-05-27 00:22:21.025 1 ERROR oslo_messaging.rpc.server result = func(ctxt, **new_args)
2020-05-27 00:22:21.025 1 ERROR oslo_messaging.rpc.server File "/usr/lib/python2.7/site-packages/cinder/backup/manager.py", line 413, in create_backup
2020-05-27 00:22:21.025 1 ERROR oslo_messaging.rpc.server self._update_backup_error(backup, six.text_type(err))
2020-05-27 00:22:21.025 1 ERROR oslo_messaging.rpc.server File "/usr/lib/python2.7/site-packages/oslo_utils/excutils.py", line 220, in __exit__
2020-05-27 00:22:21.025 1 ERROR oslo_messaging.rpc.server self.force_reraise()
2020-05-27 00:22:21.025 1 ERROR oslo_messaging.rpc.server File "/usr/lib/python2.7/site-packages/oslo_utils/excutils.py", line 196, in force_reraise
2020-05-27 00:22:21.025 1 ERROR oslo_messaging.rpc.server six.reraise(self.type_, self.value, self.tb)
2020-05-27 00:22:21.025 1 ERROR oslo_messaging.rpc.server File "/usr/lib/python2.7/site-packages/cinder/backup/manager.py", line 402, in create_backup
2020-05-27 00:22:21.025 1 ERROR oslo_messaging.rpc.server updates = self._run_backup(context, backup, volume)
2020-05-27 00:22:21.025 1 ERROR oslo_messaging.rpc.server File "/usr/lib/python2.7/site-packages/cinder/backup/manager.py", line 489, in _run_backup
2020-05-27 00:22:21.025 1 ERROR oslo_messaging.rpc.server tpool.Proxy(device_path))
2020-05-27 00:22:21.025 1 ERROR oslo_messaging.rpc.server File "/usr/lib/python2.7/site-packages/cinder/backup/drivers/ceph.py", line 933, in backup
2020-05-27 00:22:21.025 1 ERROR oslo_messaging.rpc.server volume.name, length)
2020-05-27 00:22:21.025 1 ERROR oslo_messaging.rpc.server File "/usr/lib/python2.7/site-packages/cinder/backup/drivers/ceph.py", line 657, in _backup_rbd
2020-05-27 00:22:21.025 1 ERROR oslo_messaging.rpc.server backup.container)) as client:
2020-05-27 00:22:21.025 1 ERROR oslo_messaging.rpc.server File "/usr/lib/python2.7/site-packages/cinder/volume/drivers/rbd.py", line 183, in __init__
2020-05-27 00:22:21.025 1 ERROR oslo_messaging.rpc.server self.cluster, self.ioctx = driver._connect_to_rados(pool)
2020-05-27 00:22:21.025 1 ERROR oslo_messaging.rpc.server File "/usr/lib/python2.7/site-packages/cinder/backup/drivers/ceph.py", line 300, in _connect_to_rados
2020-05-27 00:22:21.025 1 ERROR oslo_messaging.rpc.server ioctx = client.open_ioctx(pool_to_open)
2020-05-27 00:22:21.025 1 ERROR oslo_messaging.rpc.server File "/usr/lib/python2.7/site-packages/eventlet/tpool.py", line 186, in doit
2020-05-27 00:22:21.025 1 ERROR oslo_messaging.rpc.server result = proxy_call(self._autowrap, f, *args, **kwargs)
2020-05-27 00:22:21.025 1 ERROR oslo_messaging.rpc.server File "/usr/lib/python2.7/site-packages/eventlet/tpool.py", line 144, in proxy_call
2020-05-27 00:22:21.025 1 ERROR oslo_messaging.rpc.server rv = execute(f, *args, **kwargs)
2020-05-27 00:22:21.025 1 ERROR oslo_messaging.rpc.server File "/usr/lib/python2.7/site-packages/eventlet/tpool.py", line 125, in execute
2020-05-27 00:22:21.025 1 ERROR oslo_messaging.rpc.server six.reraise(c, e, tb)
2020-05-27 00:22:21.025 1 ERROR oslo_messaging.rpc.server File "/usr/lib/python2.7/site-packages/eventlet/tpool.py", line 83, in tworker
2020-05-27 00:22:21.025 1 ERROR oslo_messaging.rpc.server rv = meth(*args, **kwargs)
2020-05-27 00:22:21.025 1 ERROR oslo_messaging.rpc.server File "rados.pyx", line 508, in rados.requires.wrapper.validate_func (/builddir/build/BUILD/ceph-12.2.12/build/src/pybind/rados/pyrex/rados.c:4672)
2020-05-27 00:22:21.025 1 ERROR oslo_messaging.rpc.server File "rados.pyx", line 1203, in rados.Rados.open_ioctx (/builddir/build/BUILD/ceph-12.2.12/build/src/pybind/rados/pyrex/rados.c:12623)
2020-05-27 00:22:21.025 1 ERROR oslo_messaging.rpc.server ObjectNotFound: [errno 2] error opening pool 'new_ceph_pool'
~~~
- This is behaviour difference is not documented.
- User can potentially use this to find which pools are present in ceph.
