1. A method for real-time balancing of workload across a plurality of physical storage systems, the method comprising the steps of: (a) collecting performance data for each of the plurality of physical storage systems; (b) computing a set of overall metrics for each of the plurality of physical storage systems; (c) determining if any of the physical storage systems exceeds one or more predefined thresholds; (e) looping back to step (a), in response to determining that none of the physical storage systems are exceeding any of the one or more thresholds; and (f) selecting a virtual storage system for migration from one of the plurality of physical storage systems to a destination storage system in response to determining that at least one of the physical storage systems exceeds one or more predefined threshold.