It is necessary to edit the file
/etc/rc.d/rc.boot. Look for the line that
says "Mounting local filesystems" and insert the
vgscan and vgchange commands just before it.
You may also want to edit the the file
/etc/rc.d/init.d/halt to deactivate the volume
groups at shutdown. Insert the
command near the end of this file just after the filesystems are
unmounted or mounted read-only, before the comment that says
"Now halt or reboot"