Self-managing storage systems automate the tasks of detecting hotspots and triggering data migration to alleviate them. This paper argues that existing data migration techniques do not minimize data copying overhead incurred during reconfiguration, which in turn impacts application performance. We propose a novel technique that automatically detects hotspots and uses the bandwidth-to-space ratio metric to greedily reconfigure the system while minimizing the resulting data copying overhead. We validate our technique with simulations and a prototype implemented into the Linux Kernel. Our prototype and simulations show our algorithm successfully eliminates hotspots with a factor of two reduction in data copying overhead compared to other approaches.