libvirt users - Feb 2018 - Re: snapshot of a raw file - how to revert ?

On Thu, Feb 15, 2018 at 11:41:37AM +0100, Lentes, Bernd wrote:

[...]
> Hi,
> 
> i found that:
https://dustymabe.com/2015/01/11/qemu-img-backing-files-a-poor-mans-snapshotrollback/
> 
> I tried it and it seemed to work, although my root fs was checked
> after the commit, anything else seemed to work.  What do you think of
> this procedure ?
Instead of 'qemu-img create', I'd suggest using `virsh
snapshot-create-as` (as shown in my previous email).   This will tell
libvirt to automatically use the just created QCOW2 overlay.

But yeah, one useful bit is to use the `virt-xml` tool to point to the
desired disk image (instead of `virsh edit` that I mentioned in the
previous email):

    $ virt-xml F21server --edit target=vda \
        --disk driver_type=raw,path=./A.raw


-- 
/kashyap

----- On Feb 15, 2018, at 12:53 PM, Kashyap Chamarthy kchamart@redhat.com wrote:
> On Thu, Feb 15, 2018 at 11:41:37AM +0100, Lentes, Bernd wrote:
> 
> [...]
> 
>> Hi,
>> 
>> i found that:
>>
https://dustymabe.com/2015/01/11/qemu-img-backing-files-a-poor-mans-snapshotrollback/
>> 
>> I tried it and it seemed to work, although my root fs was checked
>> after the commit, anything else seemed to work.  What do you think of
>> this procedure ?
> 
> Instead of 'qemu-img create', I'd suggest using `virsh
> snapshot-create-as` (as shown in my previous email).   This will tell
> libvirt to automatically use the just created QCOW2 overlay.
> 
> But yeah, one useful bit is to use the `virt-xml` tool to point to the
> desired disk image (instead of `virsh edit` that I mentioned in the
> previous email):
> 
>    $ virt-xml F21server --edit target=vda \
>        --disk driver_type=raw,path=./A.raw
> 
> 
> --
Hi Kashyap,

thanks for your quick and detailed answers. Just to be complete.
The procedure in the above mentioned link does work with my old software ?

pc59093:~ # rpm -qa|grep -iE 'libvirt|kvm'
libvirt-cim-0.5.12-0.7.16
libvirt-python-1.2.5-1.102
libvirt-client-1.2.5-15.3
kvm-1.4.2-47.1
sles-kvm_en-pdf-11.4-0.33.1
libvirt-1.2.5-15.3

Bernd
 

Helmholtz Zentrum München

On Fri, Feb 16, 2018 at 01:59:01PM +0100, Lentes, Bernd wrote:

[...]
> Hi Kashyap,
> 
> thanks for your quick and detailed answers. Just to be complete.
> The procedure in the above mentioned link does work with my old software ?
It _should_ work; but please try on a test VM and see what works and
what doesn't in your environment.
> pc59093:~ # rpm -qa|grep -iE 'libvirt|kvm'
> libvirt-cim-0.5.12-0.7.16
> libvirt-python-1.2.5-1.102
> libvirt-client-1.2.5-15.3
> kvm-1.4.2-47.1
> sles-kvm_en-pdf-11.4-0.33.1
> libvirt-1.2.5-15.3
-- 
/kashyap