Well, I believe the problem is no more valid.
My code before was:
virsh qemu-agent-command $INSTANCE '{"execute":"guest-fsfreeze-freeze"}'
rbd snap create $RBD_ID --snap `date +%F-%T`
and then snapshot creation was hanging forever. I inserted a 2 second sleep.
My code after
virsh qemu-agent-command $INSTANCE '{"execute":"guest-fsfreeze-freeze"}'
sleep 2
rbd snap create $RBD_ID --snap `date +%F-%T`
And now it works perfectly. Again, I have no idea, how it solved the problem.
Thanks :)
2016-01-06 0:49 GMT+08:00 Мистер Сёма <angapov@xxxxxxxxx>:
> I am very sorry, but I am not able to increase log versbosity because
> it's a production cluster with very limited space for logs. Sounds
> crazy, but that's it.
> I have found out that the RBD snapshot process hangs forever only when
> QEMU fsfreeze was issued just before the snapshot. If the guest is not
> frozen - snapshot is taken with no problem... I have absolutely no
> idea how these two things could be related to each other... And again
> this issue occurs only when there is an exclusive lock on image and
> exclusive lock feature is enabled also on it.
>
> Do somebody else have such a problem?
>
> 2016-01-05 2:55 GMT+08:00 Jason Dillaman <dillaman@xxxxxxxxxx>:
>> I am surprised by the error you are seeing with exclusive lock enabled. The rbd CLI should be able to send the 'snap create' request to QEMU without an error. Are you able to provide "debug rbd = 20" logs from shortly before and after your snapshot attempt?
>>
>> --
>>
>> Jason Dillaman
>>
>>
>> ----- Original Message -----
>>> From: "Мистер Сёма" <angapov@xxxxxxxxx>
>>> To: "ceph-users" <ceph-users@xxxxxxxxxxxxxx>
>>> Sent: Monday, January 4, 2016 12:37:07 PM
>>> Subject: How to do quiesced rbd snapshot in libvirt?
>>>
>>> Hello,
>>>
>>> Can anyone please tell me what is the right way to do quiesced RBD
>>> snapshots in libvirt (OpenStack)?
>>> My Ceph version is 0.94.3.
>>>
>>> I found two possible ways, none of them is working for me. Wonder if
>>> I'm doing something wrong:
>>> 1) Do VM fsFreeze through QEMU guest agent, perform RBD snapshot, do
>>> fsThaw. Looks good but the bad thing here is that libvirt uses
>>> exclusive lock on image, which results in errors like that when taking
>>> snapshot: " 7f359d304880 -1 librbd::ImageWatcher: no lock owners
>>> detected". It seems like rbd client is trying to take snapshot on
>>> behalf of exclusive lock owner but is unable to find this owner.
>>> Without an exclusive lock everything is working nice.
>>>
>>> 2) Performing QEMU external snapshots with local QCOW2 file being
>>> overlayed on top of RBD image. This seems really interesting but the
>>> bad thing is that there is no way currently to remove this kind of
>>> snapshot because active blockcommit is not currently working for RBD
>>> images (https://bugzilla.redhat.com/show_bug.cgi?id=1189998).
>>>
>>> So again my question is: how do you guys take quiesced RBD snapshots in
>>> libvirt?
>>> _______________________________________________
>>> ceph-users mailing list
>>> ceph-users@xxxxxxxxxxxxxx
>>> http://lists.ceph.com/listinfo.cgi/ceph-users-ceph.com
>>>
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