Modern servers have a lot of active hardware and software that can stop working at any time. A failure can start with the operating system, storage, database, network connectivity, heat, or a number of other sources.

So, which elements do we rank highest to ensure system availability? Which hardware needs the closest monitoring? What kind of tests should we use to ensure that the software is operating as expected?

When dedicating monitoring resources to check hardware and software, we must answer several questions to distribute effort efficiently. Every test takes time, uses network resources, and must save its results to a status file. If our system checks are too frequent or numerous, we could end up overwhelming our monitor server. Failing to prioritize the alerting criteria can actually be more dangerous; if we become too accustomed to ignoring irrelevant alerts, legitimate system issues can propagate unchecked.

Thus, the first step in building a monitoring...