11.2 SYSGEN Parameters for SYS$PBDRIVER In most cases, the default settings for SYS$PBDRIVER should be appropriate, however several SYSGEN parameters are provided. Two SYSGEN parameters control SYS$PBDRIVER: SMCI_PORTS and SMCI_FLAGS. 11.2.1 SMCI_PORTS The SMCI_PORTS SYSGEN parameter controls initial load- ing of SYS$PBDRIVER. This parameter is a bitmask such that the bits 0 through 25 each represent a controller letter. If bit 0 is set, PBAx will be loaded. This is the default setting. If bit 1 is set, PBBx will be loaded, and so on all the way up to bit 25 will cause PBZx to be loaded. For OpenVMS Alpha Version 7.2, we recommend leaving this parameter at the default value of 1. Loading additional ports allows for multiple paths between Galaxy instances. For OpenVMS Alpha Version 7.2, having multiple communications channels does not provide any ad- vantages because SYS$PBDRIVER will initially not support Fast Path. A future release of OpenVMS will provide Fast Path support for SYS$PBDRIVER. When Fast Path support is enabled, instances with multiple CPUs can get improved throughput by having multiple communication channels between instances. 11.2.2 SMCI_FLAGS The SMCI_FLAGS SYSGEN parameter controls operational aspects of SYS$PBDRIVER. The only currently defined flag is bit 1. This controls whether or not the port device supports communications with itself. Supporting SCS communications to itself is primarily used for test purposes. By default, this bit will be turned off and thus support for SCS communication locally is disabled which saves system resources. This pa- rameter is dynamic and by turning this bit on, an SCS virtual circuit should soon form. Bit Mask Description 0 0 0 = Do not create local communications channels (SYSGEN default). Local SCS communications are primarily used in test situations and not needed for normal operations. Leaving this bit off saves resources and overhead. 1 = Create local communications channels. 1 2 0 = Load SYS$PBDRIVER if booting into both a Galaxy and a Cluster (SYSGEN Default). 1 = Load SYS$PBDRIVER if booting into a Galaxy. 2 4 0 = Minimal console output (SYSGEN default) 1 = Full console output, SYS$PBDRIVER will display console messages when creating communication channels and tearing down communication channels.