Data storage device providing communication between processing units

[0026]This invention is described in preferred embodiments in the following description with reference to the Figures, in which like numbers represent the same or similar elements. While this invention is described in terms of the best mode for achieving this invention's objectives, it will be appreciated by those skilled in the art that variations may be accomplished in view of these teachings without deviating from the spirit or scope of the invention.

[0027]Referring to FIG. 1, a data storage system 10 is illustrated which couples host systems 11 and 12 to data storage devices 14 and 15, via a plurality of processing units 71–74. In one embodiment of the invention, the data storage devices 14–15 are data storage libraries, and the processing units 71–74 are directors.

[0028]The host systems 11 and 12 may be embodied by a variety of types and numbers of processing units, servers, or computing systems. The data storage libraries 14 and 15 may comprise any similar libraries for storing r