Hello,

All 4 VMs on one of my oVirt cluster node shutdown for an unknown reason almost simultaneously.
Please help me to find the root cause.
Thanks.

Please note the host seems doing fine and never crash or hangs and I can migrate VMs back to it later.
Here is the exact timeline of all the related events combined from the host and the VM(s):

On oVirt host:
/var/log/vdsm/vdsm.log:
2020-06-25 15:25:16,944-0500 WARN  (qgapoller/3) [virt.periodic.VmDispatcher] could not run <function <lambda> at 0x7f4ed2f9f5f0> on ['e0257b06-28fd-4d41-83a9-adf1904d3622'] (periodic:289)
2020-06-25 15:25:19,203-0500 WARN  (libvirt/events) [root] File: /var/lib/libvirt/qemu/channels/e0257b06-28fd-4d41-83a9-adf1904d3622.ovirt-guest-agent.0 already removed (fileutils:54)
2020-06-25 15:25:19,203-0500 WARN  (libvirt/events) [root] File: /var/lib/libvirt/qemu/channels/e0257b06-28fd-4d41-83a9-adf1904d3622.org.qemu.guest_agent.0 already removed (fileutils:54)

[root@athos log]# journalctl -u NetworkManager --since=today
-- Logs begin at Wed 2020-05-20 22:07:33 CDT, end at Thu 2020-06-25 16:36:05 CDT. --
Jun 25 15:25:18 athos NetworkManager[1600]: <info>  [1593116718.1136] device (vnet0): state change: disconnected -> unmanaged (reason 'unmanaged', sys-iface-state: 'removed')
Jun 25 15:25:18 athos NetworkManager[1600]: <info>  [1593116718.1146] device (vnet0): released from master device SRV-VL

/var/log/messages:
Jun 25 15:25:18 athos kernel: SRV-VL: port 2(vnet0) entered disabled state
Jun 25 15:25:18 athos NetworkManager[1600]: <info>  [1593116718.1136] device (vnet0): state change: disconnected -> unmanaged (reason 'unmanaged', sys-iface-state: 'removed')
Jun 25 15:25:18 athos NetworkManager[1600]: <info>  [1593116718.1146] device (vnet0): released from master device SRV-VL
Jun 25 15:25:18 athos libvirtd: 2020-06-25 20:25:18.122+0000: 2713: error : qemuMonitorIO:718 : internal error: End of file from qemu monitor

/var/log/libvirt/qemu/aries.log:
2020-06-25T20:25:28.353975Z qemu-kvm: terminating on signal 15 from pid 2713 (/usr/sbin/libvirtd)
2020-06-25 20:25:28.584+0000: shutting down, reason=shutdown

=============================================================================================
On the first VM effected (same thing on others):
/var/log/ovirt-guest-agent/ovirt-guest-agent.log:
MainThread::INFO::2020-06-25 15:25:20,270::ovirt-guest-agent::104::root::Stopping oVirt guest agent
CredServer::INFO::2020-06-25 15:25:20,626::CredServer::262::root::CredServer has stopped.
MainThread::INFO::2020-06-25 15:25:21,150::ovirt-guest-agent::78::root::oVirt guest agent is down.

=============================================================================================
Packages version installated:
Host OS version: CentOS 7.7.1908:
ovirt-hosted-engine-ha-2.3.5-1.el7.noarch
ovirt-provider-ovn-driver-1.2.22-1.el7.noarch
ovirt-release43-4.3.6-1.el7.noarch
ovirt-imageio-daemon-1.5.2-0.el7.noarch
ovirt-vmconsole-1.0.7-2.el7.noarch
ovirt-imageio-common-1.5.2-0.el7.x86_64
ovirt-engine-sdk-python-3.6.9.1-1.el7.noarch
ovirt-vmconsole-host-1.0.7-2.el7.noarch
ovirt-host-4.3.4-1.el7.x86_64
libvirt-4.5.0-23.el7_7.1.x86_64
libvirt-daemon-4.5.0-23.el7_7.1.x86_6
qemu-kvm-ev-2.12.0-33.1.el7.x86_64
qemu-kvm-common-ev-2.12.0-33.1.el7.x86_64

On guest VM:
ovirt-guest-agent-1.0.13-1.el6.noarch
qemu-guest-agent-0.12.1.2-2.491.el6_8.3.x86_64