Abstract: A device, system and methods of data management are disclosed, which facilitate the implementation of improved mirroring, back-up, volume remapping, extent relocation, prefetching, caching, data reformatting, statistic gathering, and data translation, among others. A new, intelligent I/O stream splitter is disclosed that may intercept and alter an I/O stream received by the splitter from a communications link. For example, in the case of mirroring, the intelligent splitter may intercept write commands and associated data from a mainframe that target a specific storage location on a specific control unit. The splitter may then transmit the intercepted I/O stream to the targeted control unit and storage location over one link and in parallel transmit on another link an altered version of the intercepted I/O stream to another control unit, which is responsible for holding a mirrored version of the data.

Abstract: A method of creating a snapshot copy of data stored on a first direct access storage device is described. It includes the acts of receiving information identifying a set of data that is to be copied from the first direct access storage device and mapping destination locations in a second direct access storage device for each element of the set. The destination locations are in a sequence emulating a tape copy. The method also includes the acts of iterating through the set of data. For the each element of the set, the method of the present invention also includes the acts of determining if the element has already been copied to the second direct access storage device, and, if the element has not already been copied, then copying the element to its mapped location in the second direct access storage device. A corresponding system is also described.