A BladeCenter expansion unit attaches to a blade server and doubles the overall width of the server. In some configurations, multiple expansion units can attach to a single blade server. An expansion unit increases the capability of the blade server by adding memory and I/O options, storage and I/O options, or I/O options.
Several types of expansion units are available for IBM BladeCenter servers. See the BladeCenter Expansion Units: Supported Configurations Technote for a list of expansion units that are supported for each blade server. The technote does not mention the Multiprocessor Expansion Unit, however. The Multiprocessor Expansion Unit is supported only on the BladeCenter LS41 Type 7972 blade server.
Some blade servers support more than one expansion unit. Configuration requirements related to connecting multiple expansion units are described in the technote or in the documentation for the expansion unit. In some cases, you can attach only one unit of each type (for example, only one SIO expansion unit) or multiple units of the same type (for example, up to four BladeCenter PCI Express Gen 2 I/O Expansion Units).