Compaq External RAID Controller & Subsystem Infortrend Operation Manual page 241

Choose "Redundant Controller [Function]," and then press [ENTER]. (Note:
The current setting will be displayed on the screen. If this controller has
never been set as a redundant controller before, the default setting is
"Disabled". The message "Redundant Controller - Disabled" will be
displayed on the screen. Press [ENTER] to proceed.)
The message "Enable Redundant Controller in Autoconfigure Mode" will
appear. Use the arrow keys to scroll through the available options
("Primary," "Secondary," or "Autoconfigure"). Press [ENTER] on "Primary."
10-28
Power off controller 1, then power on controller 2. Set controller 2 to
"Secondary" as described above.
Power off controller 2.
Power on drives, both controllers, and host computer(s) for the settings
to take effect.
The Primary and Secondary controllers synchronize each other's
configurations at
communications path(s). Write-back cache will be disabled if no sync.
cache path exists.
Select "View and Edit SCSI Channels" from the Main Menu, the
communications path will be displayed as "RCCOM (Redundant
Controller Communications)."
frequent intervals through the established
Infortrend