Re: [libvirt] [PATCHv2 16/16] save: support qemu modifying xml on domain save/restore

["Daniel P. Berrange" <berrange redhat com>]

On Tue, Jul 19, 2011 at 10:20:39PM -0600, Eric Blake wrote:
> With this, it is possible to update the path to a disk backing
> image on either the save or restore action, without having to
> binary edit the XML embedded in the state file.
> 
> * src/qemu/qemu_driver.c (qemuDomainSaveInternal)
> (qemuDomainSaveImageOpen): Add parameter.
> (qemuDomainSaveFlags, qemuDomainManagedSave)
> (qemuDomainRestoreFlags, qemuDomainObjRestore): Update callers.
> ---
> 
> v2: new patch
> 
> Tested via:
> 
> virsh start dom
> virsh dumpxml dom > dom.xml
> ln /path/to/disk /path/to/disk2
> ln /path/to/disk /path/to/disk3
> edit dom.xml to change /path/to/disk to /path/to/disk2
> virsh save dom dom.save --xml dom.xml
> check that xml embedded in binary dom.save did change
> cp dom.xml dom.xml2
> edit dom.xml to change /path/to/disk2 to /path/to/disk3
> edit dom.xml2 to break abi, such as removing entire cdrom <disk> element
> virsh restore dom.save --xml dom.xml2 => properly failed
> virsh restore dom.save --xml dom.xml
> virsh dumpxml dom - validate that /path/to/disk3 is in use
> 
> Which means it is now possible to do:
> 
> virsh dumpxml dom > dom.xml
> virsh save dom dom.save
> use qemu-img to create new qcow2 files with backing file of the original images
> alter dom.xml to reflect the new file names
> virsh restore dom.save --xml dom.xml
> 
> to externally manage disk snapshots causing changed file names.
> 
> Not quite where I wanted to be with snapshot support, but certainly
> a step in the right direction!
> 
>  src/qemu/qemu_driver.c |   56 +++++++++++++++++++++++++++++++++--------------
>  1 files changed, 39 insertions(+), 17 deletions(-)


Daniel
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