On systems running OpenVMS Galaxy software, the Shared Memory
    Cluster Interconnect (SMCI) system parameter SMCI_PORTS controls
    initial loading of SYS$PBDRIVER. This parameter is a bit mask;
    bits 0 through 25 each represent a controller letter. If bit 0
    is set, which is the default setting, PBAx is loaded (where x
    represents the Galaxy Partition ID). If bit 1 is set, PBBx is
    loaded, and so on up to bit 25, which causes PBZx to be loaded.
    For OpenVMS Alpha Version 7.2 and later, HP recommends leaving
    this parameter at the default value of 1.

    Loading additional ports allows multiple paths between Galaxy
    instances. In the initial release of the Galaxy software, having
    multiple communications channels is not an advantage because
    SYS$PBDRIVER does not support fast path. A future release
    of OpenVMS will provide Fast Path support for SYS$PBDRIVER,
    when multiple CPUs improve throughput by providing multiple
    communications channels between instances.