We need to change the TARGET WWN of the fibre channel adapter of a
storage system that provide boot LUNs for several AIX box.

For non-rootvg disks, we can simply exportvg rmdev, change de WWN, then
cfgmgr importvg. Everything work fine.

The problem is for rootvg disks. Obviously, we can't exportvg.

As node_name and ww_name are disply-only attributes, we cannot use chdev
-P on the rootvg disks to change them permanently in the Customized
Devices object class.

What are the proper way to do it ?