1. A data processing method comprising: starting, at a workload computing device, a workload computing process associated with a target data storage, the workload computing process having a primary source of data at a source data storage; receiving, at the workload computing device, one or more data blocks of a plurality of data blocks from the source data storage necessary to run the workload computing process on the workload computing device; receiving, at the workload computing device, one or more data blocks of the plurality of data blocks from the source data storage in a first background operation while the workload computing process runs on the workload computing device; storing, at the target data storage, the one or more data blocks received in the first background operation; determining that the one or more data blocks contained in the source data storage have been transferred from the source data storage to the target data storage; in response to determining that the one or more data blocks contained in the source data storage have been transferred from the source data storage to the target data storage, switching the primary source of data of the workload computing process from the source data storage to the target data storage; wherein the method is performed by one or more computing devices in communication with the workload computing device, the source data storage and the target data storage.