Sar is a system utility that gives us many ways to examine performance on a Linux system. It provides details on all aspects of system performance including system load, CPU usage, memory use, paging, swapping, disk usage, device load, network activity, etc.
The name “sar” stands for “system activity report,” and it can display current performance, provide reports that are based on log files stored in your system’s /var/log/sa (or /var/log/sysstat) folder, or be set up to automatically produce daily reports. It’s part of sysstat – a collection of system performance monitoring tools.
To check if sar is available on your system, run a command like this:
Source:: Network World – Data Center