Measuring metrics of a host (eg: cpu usage, disk usage, disk fullness, memory residence metrics, uptime). This is often done via 3rd party monitoring systems which might utilize an on-host agent process. Alternatively, the OS itself might provide metrics visible to logged-in users via simple tools like
top or via various files in
Also, the writing and analysis of logs present on that same host. Often this analysis is done via
scping logs back to a workstation in an ad-hoc manner.