libvirt users - Oct 2015 - Storage statistics

Hi all,

I'd like to get a few storage statistics from a running vm.
I'd like to know read and write data about QCOW2 devices and about RBD
volumes.
I did try to execute a command similar to this:
virsh qemu-monitor-command vm-vnc '{ "execute":
"query-block"}'
as described here:
https://www.berrange.com/posts/2011/12/19/using-command-line-arg-monitor-command-passthrough-with-libvirt-and-kvm/
and implemented here:
https://github.com/cernceph/ceph-scripts/blob/master/tools/virsh-throttle-rbd.py

But I do not get any live data.
As example, I get this values about RBD volumes whether I do or I don't
read data from the volume inside the vm:

{
            "device": "drive-virtio-disk1",
            "inserted": {
                "backing_file_depth": 0,
                "bps": 0,
                "bps_rd": 0,
                "bps_wr": 0,
                "drv": "raw",
                "encrypted": false,
                "encryption_key_missing": false,
                "file":
"rbd:volumes/volume-791f56d7-d115-4889-ba6c-85f7795b84db:id=cinder:key=AQCxLlxTYI2gHBAAWztETyuM1Nkgu6+0ANkl1w==:auth_supported=cephx\\;none:mon_host=10.19.24.127\\:6789\\;10.19.24.128\\:6789\\;10.19.24.129\\:6789",
                "image": {
                    "cluster-size": 4194304,
                    "dirty-flag": false,
                    "filename":
"rbd:volumes/volume-791f56d7-d115-4889-ba6c-85f7795b84db:id=cinder:key=AQCxLlxTYI2gHBAAWztETyuM1Nkgu6+0ANkl1w==:auth_supported=cephx\\;none:mon_host=10.19.24.127\\:6789\\;10.19.24.128\\:6789\\;10.19.24.129\\:6789",
                    "format": "raw",
                    "virtual-size": 5368709120
                },
                "iops": 0,
                "iops_rd": 50,
                "iops_rd_max": 5,
                "iops_wr": 50,
                "iops_wr_max": 5,
                "ro": false
            },
            "io-status": "ok",
            "locked": false,
            "removable": false,
            "type": "unknown"
        }
    ]

Do I need to enable the statistics collection in a specific way?
Is there a better way of doing this?

My system is an Ubuntu 14.04.2 with libvirtd (libvirt) 1.2.2, kernel
3.13.0-55, ceph version 0.80.9.

Thanks
Giuseppe


-- 
Giuseppe Civitella
gcivitella at entermail.it