Can't create volume backup with ceph backend. ObjectNotFound: error opening pool 'volumebackups

Steps to reproduce:

- Login as admin
- Go to Project -> Compute -> Volumes
- Create a volume
- For created volume in dropdown menu select item `Create backup`
- Fill name and submit form

Expected result:
- Backup has `Available` status

Actual result:
- Backup has status `Error`

cinder-backup.log has error:
2016-09-12 10:41:16.481 20625 DEBUG oslo_db.sqlalchemy.engines [req-3110d07c-80fe-403d-803a-a983dd64538c 88d0c4a7834c47eea1e3661294d8e1fb 0e7352a68e1549608b873c8ac6450104 - - -] MySQL server mode set to STRICT_TRANS_TABLES,STRICT_ALL_TABLES,NO_ZERO_IN_DATE,NO_ZERO_DATE,ERROR_FOR_DIVISION_BY_ZERO,TRADITIONAL,NO_AUTO_CREATE_USER,NO_ENGINE_SUBSTITUTION _check_effective_sql_mode /usr/lib/python2.7/dist-packages/oslo_db/sqlalchemy/engines.py:256
2016-09-12 10:41:16.694 20625 ERROR oslo_messaging.rpc.dispatcher [req-3110d07c-80fe-403d-803a-a983dd64538c 88d0c4a7834c47eea1e3661294d8e1fb 0e7352a68e1549608b873c8ac6450104 - - -] Exception during message handling: error opening pool 'volumebackups'
2016-09-12 10:41:16.694 20625 ERROR oslo_messaging.rpc.dispatcher Traceback (most recent call last):
2016-09-12 10:41:16.694 20625 ERROR oslo_messaging.rpc.dispatcher File "/usr/lib/python2.7/dist-packages/oslo_messaging/rpc/dispatcher.py", line 138, in _dispatch_and_reply
2016-09-12 10:41:16.694 20625 ERROR oslo_messaging.rpc.dispatcher incoming.message))
2016-09-12 10:41:16.694 20625 ERROR oslo_messaging.rpc.dispatcher File "/usr/lib/python2.7/dist-packages/oslo_messaging/rpc/dispatcher.py", line 185, in _dispatch
2016-09-12 10:41:16.694 20625 ERROR oslo_messaging.rpc.dispatcher return self._do_dispatch(endpoint, method, ctxt, args)
2016-09-12 10:41:16.694 20625 ERROR oslo_messaging.rpc.dispatcher File "/usr/lib/python2.7/dist-packages/oslo_messaging/rpc/dispatcher.py", line 127, in _do_dispatch
2016-09-12 10:41:16.694 20625 ERROR oslo_messaging.rpc.dispatcher result = func(ctxt, **new_args)
2016-09-12 10:41:16.694 20625 ERROR oslo_messaging.rpc.dispatcher File "/usr/lib/python2.7/dist-packages/cinder/backup/manager.py", line 405, in create_backup
2016-09-12 10:41:16.694 20625 ERROR oslo_messaging.rpc.dispatcher self._update_backup_error(backup, context, six.text_type(err))
2016-09-12 10:41:16.694 20625 ERROR oslo_messaging.rpc.dispatcher File "/usr/lib/python2.7/dist-packages/oslo_utils/excutils.py", line 220, in __exit__
2016-09-12 10:41:16.694 20625 ERROR oslo_messaging.rpc.dispatcher self.force_reraise()
2016-09-12 10:41:16.694 20625 ERROR oslo_messaging.rpc.dispatcher File "/usr/lib/python2.7/dist-packages/oslo_utils/excutils.py", line 196, in force_reraise
2016-09-12 10:41:16.694 20625 ERROR oslo_messaging.rpc.dispatcher six.reraise(self.type_, self.value, self.tb)
2016-09-12 10:41:16.694 20625 ERROR oslo_messaging.rpc.dispatcher File "/usr/lib/python2.7/dist-packages/cinder/backup/manager.py", line 399, in create_backup
2016-09-12 10:41:16.694 20625 ERROR oslo_messaging.rpc.dispatcher self._run_backup(context, backup, volume)
2016-09-12 10:41:16.694 20625 ERROR oslo_messaging.rpc.dispatcher File "/usr/lib/python2.7/dist-packages/cinder/backup/manager.py", line 447, in _run_backup
2016-09-12 10:41:16.694 20625 ERROR oslo_messaging.rpc.dispatcher backup_service.backup(backup, device_path)
2016-09-12 10:41:16.694 20625 ERROR oslo_messaging.rpc.dispatcher File "/usr/lib/python2.7/dist-packages/cinder/backup/drivers/ceph.py", line 869, in backup
2016-09-12 10:41:16.694 20625 ERROR oslo_messaging.rpc.dispatcher self._full_backup(backup, volume_file, volume.name, length)
2016-09-12 10:41:16.694 20625 ERROR oslo_messaging.rpc.dispatcher File "/usr/lib/python2.7/dist-packages/cinder/backup/drivers/ceph.py", line 696, in _full_backup
2016-09-12 10:41:16.694 20625 ERROR oslo_messaging.rpc.dispatcher with rbd_driver.RADOSClient(self, backup.container) as client:
2016-09-12 10:41:16.694 20625 ERROR oslo_messaging.rpc.dispatcher File "/usr/lib/python2.7/dist-packages/cinder/volume/drivers/rbd.py", line 248, in __init__
2016-09-12 10:41:16.694 20625 ERROR oslo_messaging.rpc.dispatcher self.cluster, self.ioctx = driver._connect_to_rados(pool)
2016-09-12 10:41:16.694 20625 ERROR oslo_messaging.rpc.dispatcher File "/usr/lib/python2.7/dist-packages/cinder/backup/drivers/ceph.py", line 242, in _connect_to_rados
2016-09-12 10:41:16.694 20625 ERROR oslo_messaging.rpc.dispatcher ioctx = client.open_ioctx(pool_to_open)
2016-09-12 10:41:16.694 20625 ERROR oslo_messaging.rpc.dispatcher File "/usr/lib/python2.7/dist-packages/rados.py", line 667, in open_ioctx
2016-09-12 10:41:16.694 20625 ERROR oslo_messaging.rpc.dispatcher raise make_ex(ret, "error opening pool '%s'" % ioctx_name)
2016-09-12 10:41:16.694 20625 ERROR oslo_messaging.rpc.dispatcher ObjectNotFound: error opening pool 'volumebackups'

env:
cat /etc/fuel_build_id:
 495
cat /etc/fuel_build_number:
 495
cat /etc/fuel_release:
 9.0
cat /etc/fuel_openstack_version:
 mitaka-9.0
rpm -qa | egrep 'fuel|astute|network-checker|nailgun|packetary|shotgun':
 fuel-notify-9.0.0-1.mos8583.noarch
 fuel-nailgun-9.0.0-1.mos8816.noarch
 fuelmenu-9.0.0-1.mos275.noarch
 fuel-provisioning-scripts-9.0.0-1.mos8816.noarch
 fuel-setup-9.0.0-1.mos6355.noarch
 shotgun-9.0.0-1.mos90.noarch
 python-fuelclient-9.0.0-1.mos350.noarch
 fuel-agent-9.0.0-1.mos290.noarch
 python-packetary-9.0.0-1.mos149.noarch
 fuel-bootstrap-cli-9.0.0-1.mos290.noarch
 fuel-ui-9.0.0-1.mos2804.noarch
 nailgun-mcagents-9.0.0-1.mos764.noarch
 network-checker-9.0.0-1.mos74.x86_64
 fuel-utils-9.0.0-1.mos8583.noarch
 fuel-misc-9.0.0-1.mos8583.noarch
 fuel-mirror-9.0.0-1.mos149.noarch
 fuel-ostf-9.0.0-1.mos944.noarch
 fuel-openstack-metadata-9.0.0-1.mos8816.noarch
 rubygem-astute-9.0.0-1.mos764.noarch
 fuel-release-9.0.0-1.mos6355.noarch
 fuel-library9.0-9.0.0-1.mos8583.noarch
 fuel-9.0.0-1.mos6355.noarch
 fuel-migrate-9.0.0-1.mos8583.noarch

nodes:
3 controllers, 2 computes, 2 ceph-osd with replication factor 2.