Forecasting workload activity for data stored on a data storage device includes selecting at least one metric for measuring workload activity, providing at least one grouping of portions of the data according to a workload affinity determination provided for each of the portions at a subset of a plurality of time steps, where the workload affinity determination is based on each of the data portions in the group experiencing above-average workload activity during same ones of the subset of the plurality of time steps, the subset corresponding to at least one business cycle for accessing the data, and forecasting workload activity for all of the portions of data in the group based on forecasting workload activity for a subset of the data portions that is less than all of the data portions.