[libvirt-users] unattended cloning

[Kashyap Chamarthy]

On Tue, Sep 16, 2014 at 08:19:36AM +0100, Adam King wrote:
> Morning, 
> 
> I have a KVM guest running Win 2012 with MS SQL 2012. 
> In order to provide a quick method of restoring the service should the
> live server die, we've decided to clone it to a preserved state.
> Ideally, this clone should also be kept up to date and cloning should
> be done on a regular basis. 
> 
> Is there any reason not to do unattended cloning? As in, when I leave
> on a Friday afternoon, start a script to clone the guest and auto
> start the live guest? 

I don't see why not. You can do live disk mirroring as below (untill you
issue a graceful abort) . Maybe something like below (Eric or others
will correct if I missed anything):

You can invoke a live disk backup as below, which keeps on mirroring the
disk content (untill you explicitly abort):

  $ virsh blockcopy --domain f20vm vda \
        /export/dst/copy1.qcow2 \
        --wait --verbose \


When you want to end the mirroring above, you can issue a graceful
abort:

  $ virsh blockjob --domain f20vm vda \
        --abort

Then, script the `virsh` operations to create a libvirt XML and start
the new guest with the copy of the disk image (/export/dst/copy1.qcow2)

NOTE: You can also combine both the above (disk copy + abort) operations
in one command (by providing the "--finish" flag):

    $ virsh blockcopy --domain f20vm vda \
        /export/dst/copy1.qcow2 \
        --wait --finish --verbose \


On a related note, if you want to take a live disk backup _and_ 'pivot'
your live QEMU to that copy, you can try:


  $ virsh blockjob --domain f20vm vda \
        /export/dst/copy1.qcow2 \
        --wait --verbose --finish \
        --pivot 


Hope that helps a bit.

--
/kashyap