Shinken is an advanced monitoring system that is based on Nagios, but redesigned and rewritten from scratch while maintaining compatibility. It can monitor all IT devices from systems to end user applications. In case of a failure, Shinken can alert the operation engineers so they can promptly repair it. It has the same capabilities as Nagios along with more advanced built-in facilities such as load balanced and high availability monitoring.
Hades is a high availability (HA) data source. This HA data source contains two other data sources: the main one and the failover one. The HA data source exposes one of them at a time and can automatically switch between them when certain conditions are met. These conditions are highly configurable. By default, when the main data source is overloaded, the failover data source is used. The load of a data base is determined on the basis of the average execution time of some configurable SQL statement that is examined periodically. The HA data source exposes through JMX its state and also operations for manual switching between the two contained data sources in case automatic switching must be suppressed for some reason.