Thanks,

for anyone interested in this issue, I filed a bug report: https://bugs.launchpad.net/nova/+bug/1656242


Regards,
Eugen


Zitat von Mohammed Naser <mna...@vexxhost.com>:

It is likely because this has been tested with QEMU only. I think you might want to bring this up with the Nova team.

Sent from my iPhone

On Jan 12, 2017, at 11:28 AM, Eugen Block <ebl...@nde.ag> wrote:

I'm not sure if this is the right spot, but I added some log statements into driver.py.
First, there's this if-block:

       if (self._host.has_min_version(MIN_LIBVIRT_LIVESNAPSHOT_VERSION,
                                      MIN_QEMU_LIVESNAPSHOT_VERSION,
                                      host.HV_DRIVER_QEMU)
            and source_type not in ('lvm')
            and not CONF.ephemeral_storage_encryption.enabled
            and not CONF.workarounds.disable_libvirt_livesnapshot):
           live_snapshot = True
      [...]
       else:
           live_snapshot = False

And I know that it lands in the else-statement. Turns out that _host.has_min_version is "false", because of host.HV_DRIVER_QEMU. We are running on Xen hypervisors. So I tried it with host.HV_DRIVER_XEN and now nova-compute says:

[instance: 14b75237-7619-481f-9636-792b64d1be17] instance snapshotting
[instance: 14b75237-7619-481f-9636-792b64d1be17] Beginning live snapshot process

Now I'm waiting for the result, but at least the VM is still running, so it looks quite promising...

And there it is:

[instance: 14b75237-7619-481f-9636-792b64d1be17] Snapshot image upload complete

I'm testing the image now, and it works!

Now the question is, why is it defaulting to HV_DRIVER_QEMU and is it really necessary to change this directly in the code? Is there any other way?

Regards,
Eugen

Zitat von Eugen Block <ebl...@nde.ag>:

Yes, I truncated the file and uploaded it:

http://dropcanvas.com/ta7nu
(First time I used this service, please give me feedback if this doesn't work for you)

I see the "Beginning cold snapshot process" message, but I don't know why. Any help is appreciated!

Regards,
Eugen


Zitat von Mohammed Naser <mna...@vexxhost.com>:

Would you be able to share the logs of a full snapshot run with the compute node in debug?

Sent from my iPhone

On Jan 12, 2017, at 7:47 AM, Eugen Block <ebl...@nde.ag> wrote:

That's strange, I also searched for this message, but nothing there. I have debug logs enabled on compute node but I don't see anything regarding ceph. No matter, what I do, my instance is always shutdown before a snapshot is taken. What else can I try?


Zitat von John Petrini <jpetr...@coredial.com>:

Mohammed,

It looks like you may be right. Just found the permissions issue in the
nova log on the compute node.

4-e8f52e4fbcfb 691caf1c10354efab3e3c8ed61b7d89a
49bc5e5bf2684bd0948d9f94c7875027 - - -] Performing standard snapshot
because direct snapshot failed: no write permission on storage pool images

I'm going to test the change and will send an update you all with the
results.

Thank You,

___

John Petrini




Yes, we are also running Mitaka and I also read Sebastien Han's blogs ;-)

our snapshots are not happening at the RBD level,
they are being copied and uploaded to glance which takes up a lot of space
and is very slow.


Unfortunately, that's what we are experiencing, too. I don't know if
there's something I missed in the nova configs or somewhere else, but I'm
relieved that I'm not the only one :-)

While writing this email I searched again and found something:

https://specs.openstack.org/openstack/nova-specs/specs/mitak
a/implemented/rbd-instance-snapshots.html

https://review.openstack.org/#/c/205282/

It seems to be implemented already, I'm looking for the config options to set. If you manage to get nova to make rbd snapshots, please let me know ;-)

Regards,
Eugen



Zitat von John Petrini <jpetr...@coredial.com>:

Hi Eugen,

Thanks for the response! That makes a lost of sense and is what I figured was going on but I missed it in the documentation. We use Ceph as well and
I had considered doing the snapshots at the RBD level but I was hoping
there was someway to accomplish this via nova. I came across this
Sebastien
Han write-up that claims this functionality was added to Mitaka:
http://www.sebastien-han.fr/blog/2015/10/05/openstack-nova-
snapshots-on-ceph-rbd/

We are running Mitaka but our snapshots are not happening at the RBD
level,
they are being copied and uploaded to glance which takes up a lot of space
and is very slow.

Have you or anyone else implemented this in Mitaka? Other than Sebastian's
blog I haven't found any documentation on this.

Thank You,

___

John Petrini

On Wed, Jan 11, 2017 at 3:32 AM, Eugen Block <ebl...@nde.ag> wrote:

Hi,

this seems to be exptected, the docs say:

"Shut down the source VM before you take the snapshot to ensure that all
data is flushed to disk."

So if the VM is not shut down, it's freezed to prevent data loss (I
guess). Depending on your storage backend, there are other ways to
perform
backups of your VMs.
We use Ceph as backend for nova, glance and cinder. Ceph stores the
disks,
images and volumes as Rados block device objects. We have a backup script that creates snapshots of these RBDs, which are exported to our backup
drive. This way the running VM is not stopped or freezed, the user
doesn't
notice any issues. Unlike a nova snapshot, the rbd snapshot is created immediately within a few seconds. After a successful backup the snapshots
are removed.

Hope this helps! If you are interested in Ceph, visit [1].

Regards,
Eugen

[1] http://docs.ceph.com/docs/giant/start/intro/


Zitat von John Petrini <jpetr...@coredial.com>:


Hello,


I've just started experimenting with nova backup and discovered that
there
is a period of time during the snapshot where the instance becomes
unreachable. Is this behavior expected during a live snapshot? Is there
any
way to prevent this?

___

John Petrini




--
Eugen Block                             voice   : +49-40-559 51 75
NDE Netzdesign und -entwicklung AG      fax     : +49-40-559 51 77
Postfach 61 03 15
D-22423 Hamburg                         e-mail  : ebl...@nde.ag

     Vorsitzende des Aufsichtsrates: Angelika Mozdzen
       Sitz und Registergericht: Hamburg, HRB 90934
               Vorstand: Jens-U. Mozdzen
                USt-IdNr. DE 814 013 983


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--
Eugen Block                             voice   : +49-40-559 51 75
NDE Netzdesign und -entwicklung AG      fax     : +49-40-559 51 77
Postfach 61 03 15
D-22423 Hamburg                         e-mail  : ebl...@nde.ag

     Vorsitzende des Aufsichtsrates: Angelika Mozdzen
       Sitz und Registergericht: Hamburg, HRB 90934
               Vorstand: Jens-U. Mozdzen
                USt-IdNr. DE 814 013 983





--
Eugen Block                             voice   : +49-40-559 51 75
NDE Netzdesign und -entwicklung AG      fax     : +49-40-559 51 77
Postfach 61 03 15
D-22423 Hamburg                         e-mail  : ebl...@nde.ag

     Vorsitzende des Aufsichtsrates: Angelika Mozdzen
       Sitz und Registergericht: Hamburg, HRB 90934
               Vorstand: Jens-U. Mozdzen
                USt-IdNr. DE 814 013 983


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Mailing list: http://lists.openstack.org/cgi-bin/mailman/listinfo/openstack
Post to     : openstack@lists.openstack.org
Unsubscribe : http://lists.openstack.org/cgi-bin/mailman/listinfo/openstack



--
Eugen Block                             voice   : +49-40-559 51 75
NDE Netzdesign und -entwicklung AG      fax     : +49-40-559 51 77
Postfach 61 03 15
D-22423 Hamburg                         e-mail  : ebl...@nde.ag

       Vorsitzende des Aufsichtsrates: Angelika Mozdzen
         Sitz und Registergericht: Hamburg, HRB 90934
                 Vorstand: Jens-U. Mozdzen
                  USt-IdNr. DE 814 013 983



--
Eugen Block                             voice   : +49-40-559 51 75
NDE Netzdesign und -entwicklung AG      fax     : +49-40-559 51 77
Postfach 61 03 15
D-22423 Hamburg                         e-mail  : ebl...@nde.ag

       Vorsitzende des Aufsichtsrates: Angelika Mozdzen
         Sitz und Registergericht: Hamburg, HRB 90934
                 Vorstand: Jens-U. Mozdzen
                  USt-IdNr. DE 814 013 983




--
Eugen Block                             voice   : +49-40-559 51 75
NDE Netzdesign und -entwicklung AG      fax     : +49-40-559 51 77
Postfach 61 03 15
D-22423 Hamburg                         e-mail  : ebl...@nde.ag

        Vorsitzende des Aufsichtsrates: Angelika Mozdzen
          Sitz und Registergericht: Hamburg, HRB 90934
                  Vorstand: Jens-U. Mozdzen
                   USt-IdNr. DE 814 013 983


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