[libvirt-users] how to get disk snapshot size
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' size
The 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 00:00:00.000
qemu-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
participants (3)
-
Eric Blake -
Kashyap Chamarthy -
Yitao Jiang