cannot backup over 2 volumes simultaneously

[Khoi]

Hello.

I cannot backup over 2 volumes simultaneously.

Errors:

/var/lib/kolla/venv/lib/python3.8/site-packages/cinder/db/sqlalchemy/models.py:152: SAWarning: implicitly coercing SELECT object to scalar subquery; please use the .scalar_subquery() method to produce a scalar subquery.
  last_heartbeat = column_property(
/var/lib/kolla/venv/lib/python3.8/site-packages/cinder/db/sqlalchemy/models.py:160: SAWarning: implicitly coercing SELECT object to scalar subquery; please use the .scalar_subquery() method to produce a scalar subquery.
  num_hosts = column_property(
/var/lib/kolla/venv/lib/python3.8/site-packages/cinder/db/sqlalchemy/models.py:169: SAWarning: implicitly coercing SELECT object to scalar subquery; please use the .scalar_subquery() method to produce a scalar subquery.
  num_down_hosts = column_property(
Traceback (most recent call last):
  File "/var/lib/kolla/venv/lib/python3.8/site-packages/eventlet/hubs/hub.py", line 476, in fire_timers
    timer()
  File "/var/lib/kolla/venv/lib/python3.8/site-packages/eventlet/hubs/timer.py", line 59, in __call__
    cb(*args, **kw)
  File "/var/lib/kolla/venv/lib/python3.8/site-packages/eventlet/semaphore.py", line 147, in _do_acquire
    waiter.switch()
greenlet.error: cannot switch to a different thread

I tried to change but it wont work:

- connection time in mariadb to 120
- backup worker in cinder.conf to 2

My env:

Kolla Ansible Yoga on Ubuntu 20.04

My Cinder backend is SAN powerstore5000T

Thank you.

[Khoi (khoinh5)]

OK.
Fix here:
https://review.opendev.org/c/openstack/oslo.log/+/911940