[libvirt-users] KVM incremental backup using CBT

[Eric Blake]

On 10/29/2014 01:07 PM, Thomas Stein wrote:
> About the --quiesce option. Do i need to do something inside the vm? The most 
> commonly would probably be a sql server running inside the vm. Do i need to 
> tell the sql server something about the --quiesce option i use? I read this 
> article here which suggests such a procedure. Okay, it's vmware, but... Is 
> that right?

For --quiesce to work, you have to have qemu-guest-agent installed and
running in your guest, and also inform libvirt via the domain XML to
establish a channel to the guest agent.  Furthermore, if you want your
sql database to be at a stable point, you can install freeze hooks in
your guest that get invoked prior to freezing the file system and just
after thawing it (that is, qemu-guest-agent already has documented hooks
that let you do any additional prep work beyond just freezing the file
system).

A quick google search found this:
http://callecalle.uach.cl/ovirt-engine/docs/manual/en_US/html/Technical_Guide/QEMU_Guest_Agent_Overview.html

Sadly, it didn't spell out the name of where you install hook scripts
into the guest.  But this commit is pretty telling:
https://github.com/qemu/qemu/blob/master/scripts/qemu-guest-agent/fsfreeze-hook

-- 
Eric Blake   eblake redhat com    +1-919-301-3266
Libvirt virtualization library http://libvirt.org

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