In the process of engineers carry out storage array controller replacement operations, which of the following description is wrong?

In the process of engineers carry out storage array controller replacement operations, which of the following description is wrong?
A . Prior to plug the controller, make sure that the business has stopped or has switched to the peer controller.
B . before change the business to the opposite end controller, be sure to check multipathing software is installed and effective in the system on the host side.
C . confirm whether cahce dirty data has been saved.
D . must process the master/slave controller switchover, so make being replaced controller as back control.

Answer: D