Method and apparatus for selective volume swapping in a data storage device based on merging multiple sets of candidate storage devices

In an optimization dispatch process for a storage system, M storage devices are identified for an optimization analysis process to be executed to identify logical volume swaps for improving system performance. The M storage devices are identified by merging candidate storage devices obtained from separate identification algorithms employing distinct identification criteria. The analysis process is dispatched for execution based on the M storage devices until (i) a successful completion upon which a best swap has been identified, or (ii) a resource-based stop condition such as an execution time limit. M is adjusted for a subsequent iteration such that over time a desired rate of successful completions is achieved. For example, M is increased by a first amount upon a successful completion and decreased by a second amount upon the stop condition. A variety of identification algorithms can be employed, including an algorithm based on assigning swap scores to the storage devices during relatively short sample intervals.