Aspen:System Logs
From Aspen Documentation
Using system logging is incredibly helpful during development. The framework itself outputs a lot of helpful information about it's startup process and activity.
First, make sure the logging directory exists and is writable by the webserver. The default directory is logs within your installation directory.
Add the following configuration directive to your config files.
$config['enable_logging'] = true;
Point your browser to the log file within the logs folder, and take a look. By default, the framework logs information regarding the startup process, session, post, get, defined constants, configuration values, loaded libraries, and router paths/urls.
To add in your own logging statements, you use the various methods in the Log class.