A slow-disk detection method is disclosed, the method includes: periodically performing sampling in a detection period; each time sampling is performed, obtaining a first delay of data reading or writing that is performed on a hard disk in current sampling, and a first-delay-related indicator value; determining a first range to which the first-delay-related indicator value belongs; and if the first range is full, calculating a first ratio of the first delay to an average delay in a range; and each time after one detection period ends and before a next detection period starts, if a quantity of all delay-related indicator values fall within all full ranges is greater than or equal to a second threshold, calculating an average value of first ratios; and if the average value of the first ratios is greater than or equal to a third threshold, determining that the hard disk is a slow disk.