[cinder-backup] Backup is not possible from backends different than ceph

[Jan Wasilewski]

Description
===========
I tried to create a volume backup from volume which is not located on ceph backend. In my case it is a huawei dorado. It fails with information that pool None doesn't exist, even if in config I have provided information that we need to use pool backup:
backup_ceph_pool = backup

Volumes which are created on ceph backend do not have these kind of issues(backup is successfully created)

Steps to reproduce
==================
1. Stop an instance with attached volume connected to different backend than ceph(in my case huawei dorado iscsi)
2. Create a backup of this volume
3. Observe if backup is created

Expected result
===============
Backup should be successfully created

Actual result
=============
Backup creation fails with logs:
Exception during message handling: cinder.exception_Remote.VolumeBackendAPIException_Remote: Bad or unexpected response from the storage volume backend API: Pool None doesn't exist in storage.

Volume Backup is in Error state, just after creation.

Environment
===========
OpenStack Stein release after upgrade from Rocky
Cinder details:
ii cinder-api 2:14.3.1-0ubuntu1~cloud1 all Cinder storage service - API server
ii cinder-backup 2:14.3.1-0ubuntu1~cloud1 all Cinder storage service - Scheduler server
ii cinder-common 2:14.3.1-0ubuntu1~cloud1 all Cinder storage service - common files
ii cinder-scheduler 2:14.3.1-0ubuntu1~cloud1 all Cinder storage service - Scheduler server
ii cinder-volume 2:14.3.1-0ubuntu1~cloud1 all Cinder storage service - Volume server
rc python-cinder 2:13.0.9-0ubuntu1~cloud1.1 all Cinder Python 2 libraries
ii python-cinderclient 1:4.1.0-0ubuntu1~cloud0 all Python bindings to the OpenStack Volume API - Python 2.x
ii python3-cinder 2:14.3.1-0ubuntu1~cloud1 all Cinder Python 3 libraries
ii python3-cinderclient 1:4.1.0-0ubuntu1~cloud0 all Python bindings to the OpenStack Volume API - Python 3.x

Logs & Configs
==============

header of an error: http://paste.openstack.org/show/zurmIKqBRmR6bh8Kt3mj/
backend config: http://paste.openstack.org/show/9nE3InvSWrIp9myvDf8g/

error code: http://paste.openstack.org/show/F29h1VFn4PxWxMITQvPV/

[Jan Wasilewski (janwasilewski)]

Problem is solved when such dirty hack is applied for os_brick: /usr/lib/python3/dist-packages/os_brick/initiator/connectors/iscsi.py:

--- /usr/lib/python3/dist-packages/os_brick/initiator/connectors/iscsi.py.orig 2021-07-23 15:17:13.999556010 +0200
+++ /usr/lib/python3/dist-packages/os_brick/initiator/connectors/iscsi.py 2021-07-23 15:14:09.355858606 +0200
@@ -1085,12 +1085,12 @@
     def _disconnect_from_iscsi_portal(self, connection_properties):
         self._iscsiadm_update(connection_properties, "node.startup", "manual",
                               check_exit_code=[0, 21, 255])
- self._run_iscsiadm(connection_properties, ("--logout",),
- check_exit_code=[0, 21, 255])
- self._run_iscsiadm(connection_properties, ('--op', 'delete'),
- check_exit_code=[0, 21, 255],
- attempts=5,
- delay_on_retry=True)
+# self._run_iscsiadm(connection_properties, ("--logout",),
+# check_exit_code=[0, 21, 255])
+# self._run_iscsiadm(connection_properties, ('--op', 'delete'),
+# check_exit_code=[0, 21, 255],
+# attempts=5,
+# delay_on_retry=True)

     def _disconnect_connection(self, connection_properties, connections, force,
                                exc):

Then backup is able to be created.