[libvirt-users] Using qemu-kvm divre snapshot option

Alessandro Italiano
Wed, 23 Feb 2011 09:16:58 -0000

Hi,

looking at the qemu-kvm man page, it is possible to enable
snapshot for a given drive. This is what we need because we would like to start
a domain
with two drives, one on a file with snapshot=on  and an other drive  on LVM with
snapshot=off.

Unfortunately it seems that if you use libvirt the same option is not available
when you define the domain with a XML file.
I mean, I didn't find out a way to support the above use case.

So, does libvirt support the drive snapshot option as qemu-kvm does ?

[root at dom0-103-13-26-b libvirt-0.8.8]# cat /etc/issue
Scientific Linux sl54_x86_64

[root at dom0-103-13-26-b libvirt-0.8.8]# rpm -qa | grep libvirt
libvirt-0.6.3-20.1.el5_4.x86_64
libvirt-python-0.6.3-20.1.el5_4.x86_64

[root at dom0-103-13-26-b libvirt-0.8.8]# rpm -qa | grep qemu
qemu-common-0.10.5-1.el5.2.x86_64
kvm-qemu-img-83-164.el5_5.21.x86_64
qemu-system-x86-0.10.5-1.el5.2.x86_64

Below you can find a copy of the XML where we would like to add somewhere the
option snapshot

<domain type='kvm'>
 <name>centos5_b</name>
 <uuid>a973d1d4-7af6-3f41-a3c1-bea958aba98b</uuid>
 <memory>524288</memory>
 <currentMemory>524288</currentMemory>
 <vcpu>1</vcpu>
 <os>
   <type arch='x86_64'
machine='rhel5.4.0'>hvm</type>
   <boot dev='hd'/>
 </os>
 <features>
   <acpi/>
   <apic/>
   <pae/>
 </features>
 <clock offset='utc'/>
 <on_poweroff>destroy</on_poweroff>
 <on_reboot>restart</on_reboot>
 <on_crash>restart</on_crash>
 <devices>
   <emulator>/usr/libexec/qemu-kvm</emulator>
   <disk type='file' device='disk'>
     <driver name='qemu' cache='none'/>

     <target dev='vda' bus='virtio'>
   </disk>
   <disk type=block device='disk'>

     <target dev='vda' bus='virtio'>
   </disk>
   <disk type='file' device='cdrom'>
     <target dev='hdc' bus='ide'/>
     <readonly/>
   </disk>
   <interface type='bridge'>
     <mac address='00:16:36:36:70:3e'/>

     <model type='virtio'/>
   </interface>
   <serial type='pty'>
     <target port='0'/>
   </serial>
   <console type='pty'>
     <target port='0'/>
   </console>

   <graphics type='vnc' port='-1' autoport='yes'
keymap='it'/>
 </devices>
</domain>


Thanks in advance

Alessanndro

**********************************************
Alessandro Italiano
INFN-CNAF,Tier1 Farming Group
Viale Berti Pichat 6/2, 40127 Bologna, Italy
Tel: +39 051 6092751
alessandro.italiano at cnaf.infn.it
www.cnaf.infn.it
Skype#alessandroitaliano

**********************************************





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