15.3 Venafi Control Center/Configuration Wizard
Starting in 15.3 the way the log server functions and the way Venafi writes logs to the Database has changed. This has caused a different section to appear during the Configuration of 15.3. The page is titled "Log Processor" and allows you to check a box that says "Enable log event processing on this system". This will enable the server you are running the wizard on the ability to look at logs and send out notifications (ie SMTP/Email). You should only check this box if the server has access to the mail server to send out these notifications.
In Previous versions of Venafi Trust Protection Platform (14.2-15.2) There was a section in the configuration wizard that allowed you to choose which server was the log server.
Pre 15.3 screenshot
Now starting in 15.3 there is a "Log Processor" page in the configuration wizard. Before 15.3, components such as Web Admin and Aperture would send log events to a single log server over port 689. That log server would then look at the logs and decide if any of the logs met any notification rules and would then send out the notifications as necessary. The log server would also send all logs that it receives to the database. With 15.3 this process has changed. Instead of the components such as Web Admin or Aperture sending their logs to the log server over port 689, they send the logs directly to the Database. Then, which ever servers have "Log Processor" enabled will look at those logs in the database and will then evaluate the logs for notifications. The benefits of this method is that there is increased fail over and efficiency of logs. Instead of one log server, you can select multiple servers to be logs servers (given that the server has SMTP access).