IBM System Management Facilities
IBM System Management Facility (SMF) is a component of IBM's z/OS for mainframe computers, providing a standardised method for writing out records of activity to a file (or data set to use a z/OS term). SMF provides full "instrumentation" of all baseline activities running on that IBM mainframe operating system, including I/O, network activity, software usage, error conditions, processor utilization, etc.
Source: Wikipedia — IBM System Management Facilities (CC BY-SA 4.0)