Methods, apparatus, software, and system architectures for supporting virtualized system migrations and scaling. Under aspects of a method, data is automatically collected and aggregated at multiple levels by a plurality of agents for each of multiple data centers. The data includes data relating to virtual machine utilization, data relating to electrical utilization costs, data relating to data center utilization, and data relating to triggers events. The data is processed to determine whether to migrate virtual servers from a first data center to a second data center. The software architecture includes a plurality of modules including a controller, data center profile, transition triggers, power cost profile, and virtual machine package module. The agents are implemented in an agent hierarchy and configured to collect data themselves and/or aggregate data from other agents and provide an API to facilitate access to collected data and agent services.