[libvirt-users] virsh snapshot-create and blockcopy

[Kashyap Chamarthy]

On 06/10/2013 01:20 PM, Thomas Stein wrote:
> Am 10.06.13 09:07, schrieb Kashyap Chamarthy:
>> On 06/09/2013 02:46 PM, Thomas Stein wrote:
>>> Hello.
>>>
>>> I just tried the following:
>>>
>>> virsh dumpxml --security-info gentoo-template > gentoo-template.xml
>>> virsh snapshot-create gentoo-template
>>> virsh undefine gentoo-template
>>
>> Wait - is that really the command you used after "snapshot-create" ?
> 
>> Because: You cannot undefine a guest with a snapshot without first deleting its metadata
>>
>> To cleanly delete, maybe you should've done:
>>
>>   $ virsh snapshot-delete --domain gentoo-template SNAPSHOTID --metadata
> 
> Did that. But that deletes that snapshot too, no?

Yes. (I just understood what you wanted to do). Noted my details below.


> 
>>
>>> virsh blockcopy gentoo-template vda
>>> /opt/virt-backup-blockcopy/gentoo-template/gentoo-template.qcow2 --wait --verbose --finish
>>> virsh define gentoo-template.xml
>>
>> Can you also paste the output of:
>>
>>   $ qemu-img info --backing-chain \
>>   /opt/virt-backup-blockcopy/gentoo-template/gentoo-template.qcow2
> 
> hn ~ # qemu-img info --backing-chain
> /opt/virt-backup-blockcopy/gentoo-template/gentoo-template.qcow2
> image: /opt/virt-backup-blockcopy/gentoo-template/gentoo-template.qcow2
> file format: qcow2
> virtual size: 130G (139586437120 bytes)
> disk size: 30G
> cluster_size: 65536
> 
> Just to make myself clear. I want to backup the qcow image /with/ the
> internal snapshot. Is that even possible with blockcopy?

Let's try. I just did the below test (also I noted it in the URL below)

# Take an (internal) snapshot when the guest was shutdown
$ virsh snapshot-list fed18
 Name                 Creation Time             State
------------------------------------------------------------
 1370847718           2013-06-10 12:31:58 +0530 shutoff


# Start the guest
$ virsh start fed18


# Undefine the guest while it is running - this will
# make the guest transient (libvirt expects it to be 'transient')
$ virsh undefine fed18
Domain fed18 has been undefined


# List the guest
root@~$ virsh list
 Id    Name                           State
----------------------------------------------------
 3     fed18                          running

$


# Do blockcopy (it's only when the guest is "live")
$ virsh blockcopy --domain fed18 vda \
/export/backup/images/fed18.qcow2 --wait --finish --verbose
Block Copy: [ 100 %]


# Query the info of original image:
===========
root@~$ qemu-img info --backing-chain  /var/lib/libvirt/images/el6box1.qcow2
image: /var/lib/libvirt/images/el6box1.qcow2
file format: qcow2
virtual size: 10G (10737418240 bytes)
disk size: 1.2G
cluster_size: 65536
Snapshot list:
ID        TAG                 VM SIZE                DATE       VM CLOCK
1         1370853048                0 2013-06-10 14:00:48   00:00:00.000
===========
$ qemu-img snapshot -l /var/lib/libvirt/images/el6box1.qcow2
Snapshot list:
ID        TAG                 VM SIZE                DATE       VM CLOCK
1         1370853048                0 2013-06-10 14:00:48   00:00:00.000
===========

# Query info of the backup:
===========
$ qemu-img info --backing-chain  /export/backup/images/el6box1-back.qcow2
image: /export/backup/images/el6box1-back.qcow2
file format: qcow2
virtual size: 10G (10737418240 bytes)
disk size: 10G
cluster_size: 65536
===========
$ qemu-img snapshot -l /export/backup/images/el6box1-back.qcow2
===========

Hm, from what it looks, it doesn't appear to preserve the internal snapshot..

> 
>> http://kashyapc.fedorapeople.org/virt/lc-2012/live-backup-with-blockcopy.txt
>>



-- 
/kashyap