Hi,guys I wanna to get the disk snapshot size, but found nothing libvirt commands related,except qemu-img. I create two disk snapshots, but nothing return its' size [root@cskvm01 qcow2]# qemu-img info /mnt/e6758700-af68-3c06-ade3-53f5f9b93507/e2cf6551-0d2c-4382-a86c-8ba633954ff2 image: /mnt/e6758700-af68-3c06-ade3-53f5f9b93507/e2cf6551-0d2c-4382-a86c-8ba633954ff2 file format: qcow2 virtual size: 5.0G (5368709120 bytes) disk size: 1.0G cluster_size: 65536 Snapshot list: ID TAG VM SIZE DATE VM CLOCK 1 4fc42d73-8257-42bd-8807-81700fd3c689 0 2015-03-15 21:05:55 01:05:53.583 2 2fd6aeab-cb26-446d-b1c6-e8d70d33f651 0 2015-03-15 21:50:35 00:00:00.000 After wrote data to the disk, then create another snapshot [root@cskvm01 qcow2]# qemu-img info /mnt/e6758700-af68-3c06-ade3-53f5f9b93507/e2cf6551-0d2c-4382-a86c-8ba633954ff2 image: /mnt/e6758700-af68-3c06-ade3-53f5f9b93507/e2cf6551-0d2c-4382-a86c-8ba633954ff2 file format: qcow2 virtual size: 5.0G (5368709120 bytes) disk size: 3.9G cluster_size: 65536 Snapshot list: ID TAG VM SIZE DATE VM CLOCK 1 4fc42d73-8257-42bd-8807-81700fd3c689 0 2015-03-15 21:05:55 01:05:53.583 2 2fd6aeab-cb26-446d-b1c6-e8d70d33f651 0 2015-03-15 21:50:35 00:00:00.000 3 63815565-3a06-4366-a1b3-bfeb9c4a07b4 0 2015-03-15 22:22:43 00:00:00.000 VM SIZE column still show 0 Here is my environment qemu-img version 0.12.1, Copyright (c) 2004-2008 Fabrice Bellard libvirtd (libvirt) 0.10.2 CentOS release 6.5 (Final) 2.6.32-431.el6.x86_64 --- Thanks, Yitao(依涛 姜) jiangyt.github.io
On Sun, Mar 15, 2015 at 10:28:30PM +0800, Yitao Jiang wrote:> Hi,guys > I wanna to get the disk snapshot size, but found nothing libvirt commands > related,except qemu-img. > I create two disk snapshots, but nothing return its' sizeThe below does not seem like snapshots. They're *internal* qcow2 snapshots (original and delta are on the same file). A quick example of disk snapshots: List the current active device: $ virsh domblklist cirrvm Target Source ------------------------------------------------ hda /var/lib/libvirt/images/cirros-0.3.3-x86_64-disk.img Create a 'disk-only' external snapshot: $ virsh snapshot-create-as --domain cirrvm snap1 \ --diskspec vda,file=/export/vmimages/sn1.qcow2 \ --disk-only --atomic List again the current active block device: $ virsh domblklist cirrvm Target Source ------------------------------------------------ hda /export/vmimages/sn1.qcow2 Get info about the disks involved: $ qemu-img info --backing-chain /export/vmimages/sn1.qcow2 image: /export/vmimages/sn1.qcow2 file format: qcow2 virtual size: 39M (41126400 bytes) disk size: 196K cluster_size: 65536 backing file: /var/lib/libvirt/images/cirros-0.3.3-x86_64-disk.img backing file format: qcow2 Format specific information: compat: 1.1 lazy refcounts: false image: /var/lib/libvirt/images/cirros-0.3.3-x86_64-disk.img file format: qcow2 virtual size: 39M (41126400 bytes) disk size: 14M cluster_size: 65536 Format specific information: compat: 0.10 -- /kashyap> [root@cskvm01 qcow2]# qemu-img info > /mnt/e6758700-af68-3c06-ade3-53f5f9b93507/e2cf6551-0d2c-4382-a86c-8ba633954ff2 > image: > /mnt/e6758700-af68-3c06-ade3-53f5f9b93507/e2cf6551-0d2c-4382-a86c-8ba633954ff2 > file format: qcow2 > virtual size: 5.0G (5368709120 bytes) > disk size: 1.0G > cluster_size: 65536 > Snapshot list: > ID TAG VM SIZE DATE VM CLOCK > 1 4fc42d73-8257-42bd-8807-81700fd3c689 0 2015-03-15 21:05:55 > 01:05:53.583 > 2 2fd6aeab-cb26-446d-b1c6-e8d70d33f651 0 2015-03-15 21:50:35 > 00:00:00.000 > > After wrote data to the disk, then create another snapshot > [root@cskvm01 qcow2]# qemu-img info > /mnt/e6758700-af68-3c06-ade3-53f5f9b93507/e2cf6551-0d2c-4382-a86c-8ba633954ff2 > image: > /mnt/e6758700-af68-3c06-ade3-53f5f9b93507/e2cf6551-0d2c-4382-a86c-8ba633954ff2 > file format: qcow2 > virtual size: 5.0G (5368709120 bytes) > disk size: 3.9G > cluster_size: 65536 > Snapshot list: > ID TAG VM SIZE DATE VM CLOCK > 1 4fc42d73-8257-42bd-8807-81700fd3c689 0 2015-03-15 21:05:55 > 01:05:53.583 > 2 2fd6aeab-cb26-446d-b1c6-e8d70d33f651 0 2015-03-15 21:50:35 > 00:00:00.000 > 3 63815565-3a06-4366-a1b3-bfeb9c4a07b4 0 2015-03-15 22:22:43 > 00:00:00.000 > > VM SIZE column still show 0 > > Here is my environment > qemu-img version 0.12.1, Copyright (c) 2004-2008 Fabrice Bellard > libvirtd (libvirt) 0.10.2 > CentOS release 6.5 (Final) 2.6.32-431.el6.x86_64 >
On Mon, Mar 16, 2015 at 10:51:21AM +0100, Kashyap Chamarthy wrote:> On Sun, Mar 15, 2015 at 10:28:30PM +0800, Yitao Jiang wrote: > > Hi,guys > > I wanna to get the disk snapshot size, but found nothing libvirt commands > > related,except qemu-img. > > I create two disk snapshots, but nothing return its' size > > The below does not seem like snapshots.s/not seem like snapshots/not seem like disk snapshots And, by "The below" I was referring to your output from the original email (not what I wrote).> > They're *internal* qcow2 > snapshots (original and delta are on the same file). > > A quick example of disk snapshots: > > List the current active device: > > $ virsh domblklist cirrvm > Target Source > ------------------------------------------------ > hda /var/lib/libvirt/images/cirros-0.3.3-x86_64-disk.img > > Create a 'disk-only' external snapshot: > > $ virsh snapshot-create-as --domain cirrvm snap1 \ > --diskspec vda,file=/export/vmimages/sn1.qcow2 \ > --disk-only --atomic > > List again the current active block device: > > $ virsh domblklist cirrvm > Target Source > ------------------------------------------------ > hda /export/vmimages/sn1.qcow2 > > Get info about the disks involved: > > $ qemu-img info --backing-chain /export/vmimages/sn1.qcow2 > image: /export/vmimages/sn1.qcow2 > file format: qcow2 > virtual size: 39M (41126400 bytes) > disk size: 196K > cluster_size: 65536 > backing file: /var/lib/libvirt/images/cirros-0.3.3-x86_64-disk.img > backing file format: qcow2 > Format specific information: > compat: 1.1 > lazy refcounts: false > > image: /var/lib/libvirt/images/cirros-0.3.3-x86_64-disk.img > file format: qcow2 > virtual size: 39M (41126400 bytes) > disk size: 14M > cluster_size: 65536 > Format specific information: > compat: 0.10 > > -- > /kashyap > > > [root@cskvm01 qcow2]# qemu-img info > > /mnt/e6758700-af68-3c06-ade3-53f5f9b93507/e2cf6551-0d2c-4382-a86c-8ba633954ff2 > > image: > > /mnt/e6758700-af68-3c06-ade3-53f5f9b93507/e2cf6551-0d2c-4382-a86c-8ba633954ff2 > > file format: qcow2 > > virtual size: 5.0G (5368709120 bytes) > > disk size: 1.0G > > cluster_size: 65536 > > Snapshot list: > > ID TAG VM SIZE DATE VM CLOCK > > 1 4fc42d73-8257-42bd-8807-81700fd3c689 0 2015-03-15 21:05:55 > > 01:05:53.583 > > 2 2fd6aeab-cb26-446d-b1c6-e8d70d33f651 0 2015-03-15 21:50:35 > > 00:00:00.000 > > > > After wrote data to the disk, then create another snapshot > > [root@cskvm01 qcow2]# qemu-img info > > /mnt/e6758700-af68-3c06-ade3-53f5f9b93507/e2cf6551-0d2c-4382-a86c-8ba633954ff2 > > image: > > /mnt/e6758700-af68-3c06-ade3-53f5f9b93507/e2cf6551-0d2c-4382-a86c-8ba633954ff2 > > file format: qcow2 > > virtual size: 5.0G (5368709120 bytes) > > disk size: 3.9G > > cluster_size: 65536 > > Snapshot list: > > ID TAG VM SIZE DATE VM CLOCK > > 1 4fc42d73-8257-42bd-8807-81700fd3c689 0 2015-03-15 21:05:55 > > 01:05:53.583 > > 2 2fd6aeab-cb26-446d-b1c6-e8d70d33f651 0 2015-03-15 21:50:35 > > 00:00:00.000 > > 3 63815565-3a06-4366-a1b3-bfeb9c4a07b4 0 2015-03-15 22:22:43 > > 00:00:00.000 > > > > VM SIZE column still show 0 > > > > Here is my environment > > qemu-img version 0.12.1, Copyright (c) 2004-2008 Fabrice Bellard > > libvirtd (libvirt) 0.10.2 > > CentOS release 6.5 (Final) 2.6.32-431.el6.x86_64 > >-- /kashyap
On 03/15/2015 08:28 AM, Yitao Jiang wrote:> Hi,guys > I wanna to get the disk snapshot size, but found nothing libvirt commands > related,except qemu-img. > I create two disk snapshots, but nothing return its' size > > [root@cskvm01 qcow2]# qemu-img info > /mnt/e6758700-af68-3c06-ade3-53f5f9b93507/e2cf6551-0d2c-4382-a86c-8ba633954ff2 > image: > /mnt/e6758700-af68-3c06-ade3-53f5f9b93507/e2cf6551-0d2c-4382-a86c-8ba633954ff2 > file format: qcow2 > virtual size: 5.0G (5368709120 bytes) > disk size: 1.0G > cluster_size: 65536 > Snapshot list: > ID TAG VM SIZE DATE VM CLOCK > 1 4fc42d73-8257-42bd-8807-81700fd3c689 0 2015-03-15 21:05:55 > 01:05:53.583 > 2 2fd6aeab-cb26-446d-b1c6-e8d70d33f651 0 2015-03-15 21:50:35 > 00:00:00.000qemu-img info only reports the amount of storage tied up in the memory portion of an internal snapshot. If you take an internal snapshot when the guest is not running, then there is no memory state, so the size is correctly 0. There is currently no way to access the amount of the qcow2 file that is tied up by a given internal snapshot and which would be freed if that snapshot is deleted, but adding such a metric would be a job for the qemu list, and not anything libvirt can do without qemu's help. -- Eric Blake eblake redhat com +1-919-301-3266 Libvirt virtualization library http://libvirt.org