Selective migration of physical data

The system described herein allows for picking data to be moved from one physical location to another using certain criteria, such as expected activity level, to achieve load balancing or load optimization. Migrating data for a logical device includes subdividing the logical device into subsections, where each of the subsections corresponds to a particular address range of the logical device that is mapped to a physical device containing corresponding data and copying data for a first subsection from a first physical device to a second, different, physical device, where data for a second subsection is maintained indefinitely on the first physical device after copying the data for the first subsection to the second physical device. The first physical device may be provided in a different geographic location than the second physical device.