One embodiment of the invention comprises a method and apparatus for managing data transfers from memory to an input/output device where the data is stored in memory as data fragments. A first list of memory locations for the fragments is received. A sub-set of fragments for copying to at least one of a first and second buffer is selected based on fragment size. A request to copy the selected sub-set of fragments to the at least one first and second buffer is sent. A request to lock down any unselected fragments is sent. A second list of memory locations for the fragments is created. The second list comprises memory locations for the at least one first and second buffer and locked down fragments.