Fault prediction in logical networks

A method of analysing the performance of a logical system comprises measuring at least one performance parameter of a logical system; ```forming a time series of said at least one performance parameter; ```transforming said time series to a frequency domain to give transformed data; and ```comparing said transformed data with model data or recorded data to assess changes in performance of the logical system. In another embodiment the performance of a logical system is analysed by measuring at least one performance parameter and forming a time series of said parameter, then comparing the time series with modelled or previously recorded data to assess changes in performance of the system.