HP Array Controller HSG V8.7 Software - Manual (Page 64)

2–10 HSG80 User’s Guide
Selecting a Failover Mode
When selecting a failover mode, use transparent failover if you want the
failover to occur without any intervention from the host, or employ
multiple-bus failover if you want the host to send commands to the
companion array controller.
Using Transparent Failover
Transparent failover is a dual-redundant controller configuration in
which two controllers are connected to the same host and device buses.
Use this configuration if you want to use two controllers to service the
entire group of storagesets, single-disk units, and other storage devices.
Because both controllers service the same storage units, either
controller can continue to service all of the units if its companion
controller fails.
Transparent failover occurs when a controller fails or a user presses the
reset button on one of the controllers. To configure controllers for
transparent failover, mount both controllers in the same BA370 pedestal
and follow the steps in “Configuring an HSG80 Array Controller,” page
2–3.
Keep the following tips in mind if you configure controllers for
transparent failover:
n Set your controllers for transparent failover before configuring
devices. Once the devices, storagesets, and units are added to one
controller’s configuration, they are automatically added to the
other’s.
n If you decide to configure your devices before setting the
controllers for transparent failover, make sure you know which
controller has the good configuration information before specifying
SET FAILOVER COPY=. See Appendix B, “CLI Commands,” for
details about the SET FAILOVER COPY= command.
n Balance your assignment of devices. For example, in an18-device
subsystem, place 3 devices on each of the 6 ports, rather than
placing 6 devices on each of 3 ports.
n The controller to which you copy configuration information restarts
after you enter the SET FAILOVER command.