A system and method for transferring data in a library storage system. The library storage system comprises a management server including a storage policy. A media agent is connected to the management server. A plurality of storage media and a data source are connected to the media agent. The data source is divided into at least a first and a second portion of data. The portions of data are transferred from the data source to a first and second primary storage medium using a first and a second data stream respectively. The media agent then causes the first and second portion of data to be transferred from the first and second storage medium to a third auxiliary storage medium using a third combined data stream. Auxiliary copying is performed in chunks and multiple streams are copied in parallel.