CP6100 I/O Process Programming Manual

Using CP6100: Managing Lines
To switch control of a set of lines to the other controller
and the other CPU, you give either one or two commands in
sequence, depending on the configuration:
• If the controllers in the subsystem are currently owned by
different CPUs, give the ALTER PROCESS command with the PATH
option. That command switches not only the line you name, but
also all other lines controlled by the same I/O process.
• If the controllers in the subsystem are currently owned by the
same CPU, use the ALTER CIU command with the CPU option. To
specify a controller, give the logical device name of the CSM
process pair, followed by #A or #B for path A or path B. (To
determine whether the controller is primary for path A or path
B, check the PATHS paragraph in the SYSGEN configuration
file.) The command switches all lines whose primary path is
through the specified controller; it also switches the CSM if
the controller is primary for path A. Now the lines attached
to the subsystem are distributed between the CPUs. Then use
the ALTER PROCESS command with the PATH option. That command
switches the line you name, as well as all lines controlled by
that process, to the other controller.
Figures 3-6a and 3-6b illustrate these operations.
Switching lines and groups of lines is only one way to balance
the traffic. Another option is to move specific lines and
devices to different LIUs (i.e., plug a line into a different
LIU). Perhaps you can move some very busy lines to less busy
subsystems, or some busy terminals to less busy lines. Of
course, if you move a line to a different LIU, possibly to a
different 6100 subsystem, the configuration of the LIU must
exactly match the requirements of the line; if you move a
terminal to a new line, you might have to make configuration
changes to accommodate the new device.
October 1985
3-29