In the event that a controller needs to be replaced in an A3X00 storage product, you should understand how the controllers interact with the system and how to safely replace them. First off, Raid Manager is a GUI driven product, which means most "fixing" or damaged part "replacement" should be done through the GUI - not CLI (Command Line Interface). In the event a procedure fails through the GUI, you can try using the command line alternative.

Possible controller states are active, passive, offline and no controller:

Active means the controller owns luns and handles I/O requests for those luns.

Passive means the controller is acting as a spare. In an event the active controller becomes disabled, the passive controller kicks in and takes over the I/O requests to the damaged controller (if the module has RDAC failover support).

Offline means the controller is no longer receiving I/O. A controller is usually placed offline by the RDAC driver in response to a data path error. The user can manually place a controller offline, if and only if, there are two controllers in the raid module.

No controller means the selected raid module has only one controller.

If a controller pair somehow becomes active/passive you can follow these steps to put it back into an active/active state via GUI:

Go to the Maintenance & Tuning applications

Select the RAID module you want to change

Select the controller mode icon

Then select the button to switch the controller state back to active/active

Then (if applicable) balance the luns

And CLI:

# rdacutil -m 2 <raid_module_name>

Then (if applicable) balance the luns with

# rdacutil -l <luns_to_be_moved> <controller>

If you would like to swap the active/passive setup for passive/active via CLI:

# rdacutil -m 1 <raid_module_name>

And to put it back to the original active/passive setup, issue the command again:

# rdacutil -m 1 <raid_module_name>