[libvirt-users] problem cloning storage pool volume

Andrei Perietanu andrei.perietanu at klastelecom.com
Wed Feb 24 09:10:02 UTC 2016


I'm using libvirt 1.2.20. Also I noticed that if I specify the file format
in the target xml the file is cloned correctly:
destXML = """
            <volume>
              <name>"""+name+""".qcow2</name>
              <target>
                <path>/jffs2/disk0/"""+poolName+'/'+name+""".qcow2</path>
                *<format type='qcow2'/>*
                <permissions>
                  <owner>-1</owner>
                  <group>-1</group>
                  <mode>0644</mode>
                  <label>virt_image_t</label>
                </permissions>
              </target>
            </volume>"""

But it does not say anything about this part on libvirt.org. So it's either
a bug or the tutorial is not correct.

Andrei

On Mon, Feb 22, 2016 at 11:10 AM, Martin Kletzander <mkletzan at redhat.com>
wrote:

> On Fri, Feb 19, 2016 at 12:33:10PM +0000, Andrei Perietanu wrote:
>
>> On Fri, Feb 19, 2016 at 12:12 PM, Martin Kletzander <mkletzan at redhat.com>
>> wrote:
>>
>> On Fri, Feb 19, 2016 at 11:12:32AM +0000, Andrei Perietanu wrote:
>>>
>>> I'm trying to clone a volume in a storage pool and I'm following the
>>>> steps
>>>> described here:
>>>>
>>>>
>>>> http://libvirt.org/docs/libvirt-appdev-guide-python/en-US/html/libvirt_application_development_guide_using_python-Storage_Pools-Cloning.html
>>>>
>>>> My code looks like:
>>>>
>>>> destXML = """
>>>>            <volume>
>>>>              <name>"""+newDiskName+""".qcow2</name>
>>>>              <target>
>>>>
>>>> <path>/jffs2/disk0/"""+poolName+'/'+newDiskName+""".qcow2</path>
>>>>                <format type='qcow2'/>
>>>>                <permissions>
>>>>                  <owner>-1</owner>
>>>>                  <group>-1</group>
>>>>                  <mode>0644</mode>
>>>>                  <label>virt_image_t</label>
>>>>                </permissions>
>>>>              </target>
>>>>            </volume>"""
>>>>
>>>> srcDisk = tmpPool.storageVolLookupByName(vDisk)
>>>> newVol = sp.createXMLFrom(destXML,srcDisk, 0)
>>>>
>>>> According to the steps described in the link, this should be it; but I
>>>> can't start any VM that are using this volume.
>>>>
>>>> Also comparing the volume XML files for src/dest it looks like the
>>>> format
>>>> is not copied over:
>>>> source:
>>>> <volume type='file'>
>>>>  <name>k.qcow2</name>
>>>>  <key>/jffs2/disk0/sp/vDisk.qcow2</key>
>>>>  <source>
>>>>  </source>
>>>>  <capacity unit='bytes'>3221225472</capacity>
>>>>  <allocation unit='bytes'>332075008</allocation>
>>>>  <target>
>>>>    <path>/jffs2/disk0/sp/vDisk.qcow2</path>
>>>>    *<format type='qcow2'/>*
>>>>    <permissions>
>>>>      <mode>0644</mode>
>>>>      <owner>0</owner>
>>>>      <group>0</group>
>>>>    </permissions>
>>>>    <timestamps>
>>>>      <atime>1455879195</atime>
>>>>      <mtime>1455879171</mtime>
>>>>      <ctime>1455879171</ctime>
>>>>    </timestamps>
>>>>  </target>
>>>>
>>>>
>>>> dest:
>>>> <volume type='file'>
>>>>  <name>newDiskName.qcow2</name>
>>>>  <key>/jffs2/disk0/sp/newDiskName.qcow2</key>
>>>>  <source>
>>>>  </source>
>>>>  <capacity unit='bytes'>3221225472</capacity>
>>>>  <allocation unit='bytes'>326868992</allocation>
>>>>  <target>
>>>>    <path>/jffs2/disk0/sp/newDiskName.qcow2</path>
>>>>    *<format type='raw'/>*
>>>>
>>>>
>>>
>>> So there are two bugs here, probably.  Does this go away if you refresh
>>> the pool?
>>>
>>>          No, refreshing the pool does not help. The problem is not that I
>> don't see the new volume, the problem is I get a "raw" file instead of
>> "qcow2"
>>
>>
> I know, I wanted to see whether that format changed.  Are those files
> really cloned?  I tried the same thing you did and I have the right
> format there.  What libvirt version are you running?
>
>
>
>>> The other thing is that it doesn't matter what's here, you should
>>> explicitly specify the format in the domain XML anyway.  Do you do that?
>>>
>>>       The tutorial I followed (libvirt.org) says:
>> "Cloning a storage volume is similar to creating a new storage volume,
>> except that an existing storage volume is used for most of the attributes.
>> Only the name and permissions in the XML parameter are used for the new
>> volume, everything else is inherited from the existing volume."
>> So I don't specifically mention the file formal in the xml for the new
>> volume.
>>
>>
>>>    <permissions>
>>>
>>>>      <mode>0644</mode>
>>>>      <owner>0</owner>
>>>>      <group>0</group>
>>>>    </permissions>
>>>>    <timestamps>
>>>>      <atime>1455878686</atime>
>>>>      <mtime>1455878681</mtime>
>>>>      <ctime>1455878681</ctime>
>>>>    </timestamps>
>>>>  </target>
>>>> </volume>
>>>>
>>>> I this a bug in  libvirt->createXMLFrom ?? Or am I missing something?
>>>>
>>>> Thanks,
>>>> Andrei
>>>>
>>>> --
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-- 
 

The information transmitted is intended only for the person or entity to 
which it is addressed and may contain confidential and/or privileged 
material. Any review, retransmission, dissemination or other use of or 
taking of any action in reliance upon this information by persons or 
entities other than the intended recipient is prohibited. If you receive 
this in error please contact the sender and delete the material from any 
computer immediately. It is the policy of Klas  Limited to disavow the 
sending of offensive material and should you consider that the material 
contained in the message is offensive you should contact the sender 
immediately and also your I.T. Manager.

Klas Telecom Inc., a Virginia Corporation with offices at 1101 30th St. NW, 
Washington, DC 20007.

Klas Limited (Company Number 163303) trading as Klas Telecom, an Irish 
Limited Liability Company, with its registered office at Fourth Floor, One 
Kilmainham Square, Inchicore Road, Kilmainham, Dublin 8, Ireland.
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