Logging and Archiving in scada systems: The terms logging and archiving are often used to describe the same facility.
Logging and Archiving in SCADA systems
However, logging can be thought of as medium-term storage of data on disk, whereas archiving is long-term storage of data either on disk or on another permanent storage medium.
Logging is typically performed on a cyclic basis, i.e., once a certain file size, time period or number of points is reached the data is overwritten.
Logging of data can be performed at a set frequency, or only initiated if the value changes or when a specific predefined event occurs. Logged data can be transferred to an archive once the log is full.
The logged data is time-stamped and can be filtered when viewed by a user. The logging of user actions is in general performed together with either a user ID or station ID. There is often also a VCR facility to play back archived data.