This article provides an overview of various server monitoring tools, including Nagios Core, Ganglia, CollectD, Spiceworks, Cacti, Zabbix, Icinga, OpenNMS, and WhatsUp Gold. It compares their features and capabilities in areas such as disk usage, CPU monitoring, process monitoring, bandwidth monitoring, and overall availability. The article also discusses the importance of server monitoring, the impact of failure prediction, and the architecture of server availability monitoring tools.