'Get local storage info of the compute node in GB.
:returns: A dict containing:
:total: How big the overall usable filesystem is (in gigabytes)
:free: How much space is free (in gigabytes)
:used: How much space is used (in gigabytes)'

@staticmethod
def _get_local_gb_info():

    if (CONF.libvirt.images_type == 'lvm'):
        info = lvm.get_volume_group_info(CONF.libvirt.images_volume_group)
    elif (CONF.libvirt.images_type == 'rbd'):
        info = LibvirtDriver._get_rbd_driver().get_pool_info()
    else:
        info = libvirt_utils.get_fs_info(CONF.instances_path)
    for (k, v) in info.items():
        info[k] = (v / units.Gi)
    return info
