[Libguestfs] How to use libguestfs access LVM as non-root user?

Hi, Following code snippet, running as non-root user, will throw up a 'Permission denied' RuntimeError. Could someone kindly guide me the correct way to handle LVM disk as non-root user? Cause as http://libguestfs.org homepage claims, "libguestfs doesn't need root permissions." A little confused somehow. import guestfs g = guestfs.GuestFS() g.add_drive_opts("/dev/vg0/disk1", format="raw") Thanks! -- Qiu Yu