[ovirt-users] Bug in Snapshot Removing

[Adam Litke]

Hello Soeren.

I've started to look at this issue and I'd agree that at first glance
it looks like a libvirt issue.  The 'cannot acquire state change lock'
messages suggest a locking bug or severe contention at least.  To help
me better understand the problem I have a few questions about your
setup.

>From your earlier report it appears that you have 15 VMs running on
the failing host.  Are you attempting to remove snapshots from all VMs
at the same time?  Have you tried with fewer concurrent operations?
I'd be curious to understand if the problem is connected to the
number of VMs running or the number of active block jobs.

Have you tried RHEL-7.1 as a hypervisor host?

Rather than rebooting the host, does restarting libvirtd cause the VMs
to become responsive again?  Note that this operation may cause the
host to move to Unresponsive state in the UI for a short period of
time.

Thanks for your report.

On 31/05/15 23:39 +0000, Soeren Malchow wrote:
>And sorry, another update, it does kill the VM partly, it was still pingable when i wrote the last mail, but no ssh and no spice console possible
>
>From: Soeren Malchow <soeren.malchow at mcon.net<mailto:soeren.malchow at mcon.net>>
>Date: Monday 1 June 2015 01:35
>To: Soeren Malchow <soeren.malchow at mcon.net<mailto:soeren.malchow at mcon.net>>, "libvirt-users at redhat.com<mailto:libvirt-users at redhat.com>" <libvirt-users at redhat.com<mailto:libvirt-users at redhat.com>>, users <users at ovirt.org<mailto:users at ovirt.org>>
>Subject: Re: [ovirt-users] Bug in Snapshot Removing
>
>Small addition again:
>
>This error shows up in the log while removing snapshots WITHOUT rendering the Vms unresponsive
>
>—
>Jun 01 01:33:45 mc-dc3ham-compute-02-live.mc.mcon.net libvirtd[1657]: Timed out during operation: cannot acquire state change lock
>Jun 01 01:33:45 mc-dc3ham-compute-02-live.mc.mcon.net vdsm[6839]: vdsm vm.Vm ERROR vmId=`56848f4a-cd73-4eda-bf79-7eb80ae569a9`::Error getting block job info
>                                                                  Traceback (most recent call last):
>                                                                    File "/usr/share/vdsm/virt/vm.py", line 5759, in queryBlockJobs…
>
>—
>
>
>
>From: Soeren Malchow <soeren.malchow at mcon.net<mailto:soeren.malchow at mcon.net>>
>Date: Monday 1 June 2015 00:56
>To: "libvirt-users at redhat.com<mailto:libvirt-users at redhat.com>" <libvirt-users at redhat.com<mailto:libvirt-users at redhat.com>>, users <users at ovirt.org<mailto:users at ovirt.org>>
>Subject: [ovirt-users] Bug in Snapshot Removing
>
>Dear all
>
>I am not sure if the mail just did not get any attention between all the mails and this time it is also going to the libvirt mailing list.
>
>I am experiencing a problem with VM becoming unresponsive when removing Snapshots (Live Merge) and i think there is a serious problem.
>
>Here are the previous mails,
>
>http://lists.ovirt.org/pipermail/users/2015-May/033083.html
>
>The problem is on a system with everything on the latest version, CentOS 7.1 and ovirt 3.5.2.1 all upgrades applied.
>
>This Problem did NOT exist before upgrading to CentOS 7.1 with an environment running ovirt 3.5.0 and 3.5.1 and Fedora 20 with the libvirt-preview repo activated.
>
>I think this is a bug in libvirt, not ovirt itself, but i am not sure. The actual file throwing the exception is in VDSM (/usr/share/vdsm/virt/vm.py, line 697).
>
>We are very willing to help, test and supply log files in anyway we can.
>
>Regards
>Soeren
>

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-- 
Adam Litke