1. A method for characterizing a computer system using a pattern-recognition model, the method comprising: in one or more computer systems, performing operations for: monitoring values for an environmental parameter from a set of sensors associated with the computer system; calculating a baseline for the environmental parameter based on the monitored values from a subset of the set of sensors; subtracting the baseline from the monitored values from sensors in the set of sensors to produce compensated values; using the compensated values as inputs to the pattern-recognition model, which produces estimates for the compensated values based on correlations between the compensated values learned during a training phase; calculating residuals by subtracting the estimates for the compensated values from the compensated values; and analyzing the residuals to characterize the computer system.