When you create a volume group, by default, it is activated. Sometimes you may need to activate it manually to make the kernel aware of volume groups.
To activate,
# vgchange -ay my_vg_name
To De-activate,
# vgchnage -an my_vg_name
A command to activate the VG in a cluster?
To activate exclusively on one node,
# vgchange -aey my_vg_name
To deactivate exclusively on one node,
# vgchange -aen my_vg_name
To activate only on the local node,
# vgchange -aly my_vg_name
To deactivate only on the local node,
# vgchange -aln my_vg_name