Hi, I see that recently the last-update field has been added to the balloon statistics, this is how it looks like from Python: [(<libvirt.virDomain object at 0x7fb45b7faa50>, {'balloon.rss': 960048L, 'balloon.swap_in': 0L, 'balloon.usable': 1676424L, 'balloon.unused': 1376188L, 'balloon.major_fault': 816L, 'balloon.swap_out': 0L, 'balloon.current': 2097152L, 'balloon.maximum': 2097152L, 'balloon.available': 2048364L, 'balloon.minor_fault': 460160L, 'balloon.last-update': 1476213030L})] As you can see, there's an inconsistency as all the other members use underscore (_), not dash (-). This actually matters with the PCP plugin since PCP metric names can contain _ but not -. Now that last-update is part of the API in 2.3 I guess it's too late to change this but it would nice if in the future the member names could be kept consistent and underscore used for new members, as it has been so far. Thanks, -- Marko Myllynen