HP XP Array Manager Software - Manual (Page 67)

Figure 38 Ports in High Speed Mode or Initiator/External MIX mode
If High Speed mode is applied to the four ports in a port block, only two of the ports can be used for
connecting the host. When hosts issue I/Os to ports, the I/Os will be processed by processors on
channel adapters. I/Os to each port will be processed by only one processor in Standard mode, but
by two processors in High Speed mode. Therefore, ports in High Speed mode can process I/Os faster
than ports in Standard mode. By balancing the workloads on the processors, a greater improvement
can be expected with the system performance.
You cannot change standard mode to high-speed mode or vice versa while you are online to the hosts.
You will need to reboot the hosts after changing the mode.
To change the configuration of a port that is being used, you must perform a backup operation before
changing the port configuration.
XP24000 LUN Manager User's Guide 67