Collectl is a lightweight performance monitoring tool capable of reporting interactively as well as logging to disk. It reports statistics on cpu, disk, infiniband, lustre, memory, network, nfs, process, quadrics, slabs and more in easy to read format.
Upsilon is a distributed, flexible and extensible system monitoring application.
WhoisUP monitors hosts via ICMP and shows the status in a web page. When a host is down, the script can send mail, syslog message, open a popup message or play a sound.
Moreover, the script checks if the host exceeds the latency threshold limit.