Comment 3 for bug 1724636

I wonder if it's a dup of https://bugs.launchpad.net/tripleo/+bug/1701485

I have to check the logs but as said in comment #1, this looks a discrepancy
between the mysql pid which is running and the permission of /var/lib/mysql
on disk.

So it's either the new containerized mysql service that tries to access the
DB on disk before it has been chown to kolla's mysql uid, or it's the old
galera pid which failed to stop during the upgrade and which cannot access
the DB on disk anymore.