Pulsar: An extensible tool for monitoring large unix sites

Many problems can crop up unexpectedly on Unix computers, and the administrator must be able to detect and react to these problems quickly. If a site has more than a few computers, the effort needed to keep abreast of problems can lead to unresponsive administration. Pulse monitors form a simple but effective tool to assist the administrator in this task. This paper describes the Pulsar pulse-monitor package. It is composed of a presenter, which provides a graphical user interface to the administrator, a set of individual pulse monitors, which examine aspects of the status on a host and communicate their results to the presenter, and a scheduler, which executes pulse monitors according to the frequency specified by its configurartion files. The set of pulse monitors is easily extended by the administrator to provide warnings about any situataion that can be algorithmically detected.