A system for assessing the performance of an electrophotographic marking machine is provided, wherein data from several different inputs are gathered in two distinct sets having different frequencies. A high-frequency data set includes parameters typically recorded with each print made, and provide an electrophotographic history which is used in deducing the cause of malfunctions. The lower-frequency data are typically recorded at the time of each autosetup, and provide electrophotographic trend information which is used as a predictor of component and consumable lifetimes. In each data set, only data over an appropriately selected period maintained on a first-in, first-out basis. This system has the advantage of simultaneously providing an intensive recent history for tracing faults, and enabling long-term trends to be discerned without being buried in a redundant excess of data.