While there is an undisputed dominance of Windows based systems and applications, there are still great a deal of legacy and modern applications built on UNIX platforms. In addition to respected and well known UNIX flavors such as HP/UX, Sun Solaris, and IBM AIX, the quick expansion of Linux has caused the creation and porting of popular applications to UNIX which is known for its stability and expandability. UNIX/Linux have also became major platforms for J2EE based systems, from Apache Web servers to WebSphere application servers to Oracle database servers.
Therefore, it is no wonder that HP LoadRunner and HP Performance Center include tools to access UNIX operating system performance counters in order to trace the behavior of the application under test. While UNIX flavors may differ on specific commands and their options, they all provide various built-in facilities to gather, display and reuse performance-related information. These facilities use a variety of sampling techniques to generate interval performance monitoring data that is extremely useful in diagnosing performance problems. They are designed to be efficient enough so that you can run them continuously with minimal impact.