The following general tips can help you get started when troubleshooting issues in OpenStack:
Set debug = true and verbose = true in the various configuration files to help you diagnose problems. On some configuration files, you can look for a placeholder value which is commented out and which you can toggle to enable verbose logging.
When you make changes to a component's configuration file, restart the services for the component to make the changes effective.
Use the tail -30 `svcs -L service-name command that provides you with information from the SMF log. If you enabled debugging as well as verbose logging, you might need to increase the lines that you specify for the tail command.
Horizon processes go through Apache. Thus, to diagnose Horizon, enable debug = True in the /etc/openstack_dashboard/local_settings.py file. Django errors are then generated on the web page.
Nova components are built on top of Oracle Solaris zones. Thus, you can also refer to logs in /var/log/zones to troubleshoot Nova issues.