Workload on an aggregation of storage devices can be quantified in terms of demand on the aggregation of storage devices and demand on logical storage containers configured on the aggregation of storage devices. The demand on the aggregation of storage devices and the demand on logical storage containers thereon are calculated in a manner that captures demand on both storage capacity and performance capability. Capturing demand on both storage capacity and performance capability facilitates intelligent management that accounts for the relationship between storage capacity and performance capability. This allows the owner/operator of the storage equipment to use storage capacity at a desired (or requested) performance.