Hello i'd like to define a meter which aggregates (sums up) all space used by images. Right now, I have a "image.size" value for each image stored into glance service. I'd like to define a new meter like "allimages.size" which sums up all images size, is this possible? I've been reading http://docs.openstack.org/admin-guide/telemetry-data-collection.html but didn't find a clear example.... Any hint available? Thanks in advance J.