Zabbix

First things first, what is Zabbix and why use it?

I have personally been using it since version 1.2; the Zabbix site describes it as follows:

"With Zabbix, it is possible to gather virtually limitless types of data from the network. High-performance real-time monitoring means that tens of thousands of servers, virtual machines, and network devices can be monitored simultaneously. Along with storing the data, visualization features are available (overviews, maps, graphs, screens, and so on), as well as very flexible ways of analyzing the data for the purpose of alerting.

Zabbix offers great performance for data gathering and can be scaled to very large environments. Distributed monitoring options are available with the use of Zabbix proxies. Zabbix comes with a web-based interface, secure user authentication, and a flexible user permission schema. Polling and trapping is supported, with native high-performance agents gathering data from virtually any popular operating system;...