[Users] oVirt support for backup/restore

[Ayal Baron]

----- Original Message -----
> sön 2013-04-21 klockan 08:42 -0400 skrev Ayal Baron:
> 
> 
> 
> ----- Original Message -----
> > On 04/19/2013 11:46 AM, Gianluca Cecchi wrote:
> > > On Fri, Apr 19, 2013 at 9:58 AM, Itamar Heim wrote:
> > >
> > >>
> > >> qemu-guest-agent isn't ovirt/rhev-guest-agent.
> > >> now that qemu started their own guest agent, ovirt/rhev-guest-agent
> > >> isn't
> > >> used for things covered by the qemu-guest-agent.
> > >
> > > Ah, ok.
> > > SO after reading
> > > http://wiki.libvirt.org/page/Qemu_guest_agent
> > > some questions
> > >
> > > can we use ootb qemu-guest-agent with ovirt 3.2.1 if we have for
> > > example a CentOS 6 guest (with qemu-guest-agent-0.12.1.2-2.355)?
> > > Does oVirt create a virtio-serial port to communicate with libvit and
> > > does it use libvirt with any options to quiesce  fs on guest?
> >
> > iirc, it should work - testing/feedback would be welcome.
> 
> I believe vdsm does not create the virtio-serial port when starting the VM,
> so you'd have to modify this behaviour with hooks [1].
> Once you do that, whenever you create a live snapshot vdsm will notify
> libvirt to quiesce first.
> Note that afaik, quiesce in qemu-ga is only supported for Linux guests.
> 
> 
> Really cool to hear how things are progressing! The qemu-ga quiesces what
> exactly? The guest filesystem? What about potential applications that might

Yes, it quiesces xfs/ext3/ext4 (I don't recall wrt btrfs) file systems.

> be running inside the guest? Can you call live snapshots of a linux guest
> "Application Consistent"?

Linux has no such infrastructure atm.  There are upstream patches for qemu-ga to support calling hooks before and after quiesce to allow users to freeze their apps so that the snapshot would be application consistent.  This will require users to place their scripts inside the guest of course.

> 
> The good thing about Microsoft VSS is that MS applications are registered to
> VSS so that when you trigger VSS to quiece, all of the other applications
> are told to pause as well.

Indeed, there have been many discussions around this and there is a lot of interest around this topic, but I haven't seen any accepted solution as of yet.

> 
> /Karli
> 
> 
> 
> VSS quiesce support patches have been submitted, but I'm not sure what the
> status is there yet.
> 
> [1] Hooks preso: http://www.ovirt.org/File:OVirt-hooks-netapp-jan2013.odp
> 
> >
> > >
> > > Can one use as an alternative the command fsfreeze in CentOS 6.4 guest
> > > (even if in tech preview) as in :
> > > https://access.redhat.com/site/documentation/en-US/Red_Hat_Enterprise_Linux/6/html/Technical_Notes/storage.html
> > >
> >
> > what i remember is that it supposed to be pluggable/configurable for you
> > to run the relevant commands you want.
> > ayal may remember better
> >
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> 
> --
> 
> Med Vänliga Hälsningar
> -------------------------------------------------------------------------------
> Karli Sjöberg
> Swedish University of Agricultural Sciences
> Box 7079 (Visiting Address Kronåsvägen 8)
> S-750 07 Uppsala, Sweden
> Phone:  +46-(0)18-67 15 66
> karli.sjoberg at slu.se<mailto:karli.sjoberg at adm.slu.se>
>