You might need to reconfigure the system under several conditions, including:
Board addition: When adding a board, you must execute the reconfiguration sequence to configure the I/O devices associated with the board.
Board removal: If you remove a board that is not to be replaced, you may (but do not have to) execute the reconfiguration sequence to clean up the /dev links for disk devices.
Board replacement: If you remove a board and then insert it into a different slot, or replace a board with another board that has different I/O devices, you must execute the reconfiguration sequence to configure the I/O devices associated with the board. However, if you replace a board with another board that hosts the same set of I/O devices, inserting the replacement into the same slot, you do not need to execute the reconfiguration sequence. But be sure to insert a replacement into the same slot that was vacated to retain the original /dev link names.