An administrator's work does not end with the installation and configuration of Moodle and the Operating System. Monitoring the server must be a regular part of service maintenance. If there is any problem in the way some part of the system works it can produce total loss of service or massive slowdown and thus prevent your users from accessing the website. In this chapter we will talk about ways of monitoring the status of Moodle and underlying OS components with the purpose of early detection and prevention of any kind of problems. The content is presented in the sections based on the tools and techniques available within Moodle or within OS: