Sysstat

Sysstat is a package of command-line tools for monitoring system performance and usage on Linux. Many of the utilities are familiar from commercial Unix systems, and the project has been maintained for more than two decades. It is released under the GPL-2.0 license and written in C.

The reporting tools include iostat for CPU and block-device statistics, mpstat for per-processor figures, pidstat for per-process I/O, CPU, and memory use, tapestat for tape drives, and cifsiostat for CIFS file systems. The collection side centers on sar, which gathers and stores system activity data, and sadf, which formats the saved data for other tools. Collection can be scheduled with cron or systemd.

Because it only needs a Linux host and no external service, sysstat is a common first step for diagnosing slow servers and for keeping a history of resource use that can be reviewed after an incident. It suits system administrators, DevOps engineers, and developers who need lightweight metrics without deploying a full monitoring stack.