1. A design apparatus, comprising: a non-transitory machine readable medium having at least one design structure for a first memory module recorded thereon, wherein the first memory module comprises: a plurality of addressable storage locations for storing data; a first interface for receiving data access commands for accessing data stored in said addressable storage locations; control logic which supports a plurality of modes of operation of said first memory module, including a first mode and a second mode; wherein, in said first mode of operation, said first memory module re-transmits a plurality of copies of at least some said data access commands received in said first interface, each copy being transmitted using a respective second interface of a plurality of second interfaces to a respective one or more memory modules other than said first memory module; wherein, in said first mode of operation, a first set of I/O ports is used for transmitting data read from storage locations in said first memory module to an access control module responsive to said data access commands; wherein, in said second mode of operation, said control logic determines, with respect to each data access command of said data access commands received by said first interface, whether the respective data access command addresses a data storage location in said first memory module, and (a) accesses a corresponding data storage location in said first memory module if the respective data access command addresses a data storage location in said first memory module, and (b) re-transmits a single copy of the respective data access command if the respective data access command does not address a data storage location in said first memory module, the single copy being re-transmitted to another memory module; and wherein, in said second mode of operation, a second set of I/O ports is used for transmitting data read from storage locations in said first memory module to an access control module responsive to said data access commands, said first set of I/O ports containing at least one I/O port, said second set of I/O ports containing a greater number of I/O ports than said first set of I/O ports.