[smnv]

What about http://cacti.net/ ? With Weathermap plugin it is quite good thing for performance monitoring. THold and Monitor plugins are for availability monitoring and alerting. It scales very good with Boost plugin, I had 3000+ hosts, 60000+ datasources with total poll time within one minute.

Many prefer Cacti to Zabbix because the latter is clunky and confusing compared to Cacti's simple straightforward approach with plugins.

But I am actually wondering, how alive is Cacti now, because its releases are constantly postponed, and forum is not as alive as it used to be.

[teh_klev]

Cacti is just a graphing tool that sits on top of RRDTool . It doesn't provide up/down monitoring and host/service check scheduling, it doesn't provide features such as alert escalation logic, and a whole bunch of other fairly important things that a monitoring engine such as Nagios does.

[jlgaddis]

Cacti serves a very different purpose, IMO. Up/down monitoring is not a core feature and, honestly, it's not that good at it.