Described herein are methods, systems and machine-readable media for migrating data between storage devices of a storage array. A metric is used to measure the optimality of candidate data migrations, the metric taking into account capacity balance and proper data striping. Candidate migrations are evaluated against the metric. The candidate migration that ranks as the best migration according to the metric may be carried out. This process of evaluating candidate migrations and carrying out the best candidate migration may be iterated until data is properly distributed among the storage devices of the storage array.