When you installed VxVM, you more than likely ran vxinstall to configure rootdg. During this process, the nodename was placed int a special text file called /etc/vx/volboot <DISCLAIMER> DO not edit this file manually !, you are likely to stop vxvm working </DISCLAIMER>.
At boot time, this file gets read by vxconfigd and the nodename inside is used to as vxvm's reference to the system.
There is no problem in changing the nodename of a system (/etc/nodename), as
vxvm will continue to use the name referenced in volboot. i.e if you
changed the system name and reboot, vxvm will import rootdg and the other
auotimported disk groups as normal. What you may see, is that some vxvm
commands will display the old hostname. If you want everything to look
same, you can run the command "vxdctl hostid new_hostname" and this will
change the hostid (hostname) stored in the volboot file AND all private
regions of disks that are currently imported to that of the new name