12:17 p.m.
Hi,
“I'm assuming it used ssh as the hosts in question have a configuration problem with
their power management and cannot be reset currently by the PDU”
It is interesting to find the events in logs on ovengine really doing reboot of ovirt
hosts via SSH in this case/any cases.
I guess that /var/log/messages and probably some ovengine logs should provide evidence if
it is the case (and ovengine logs can contain additional information, what is
functionality behind
‘restart host that lost a connection to storage domain’
BR,
Konstantin
From: Patrick Hibbs <hibbsncc1701(a)gmail.com>
Date: Wednesday, 30 November 2022 at 16:31
To: "users(a)ovirt.org" <users(a)ovirt.org>
Subject: [ovirt-users] Re: Forced restart when losing communication with the Storages
Hello,
I've seen something similar to this too. Although, for me it occurred when a
standalone engine attempted to allocate a new disk on a Gluster storage. While the
cluster's VMs were experiencing high virtual disk I/O. (Found out later they were
doing updates at an odd time...)
The result was random VMs being forced off until it had cleared enough of the bottleneck,
and one host was rebooted. After around 3 minutes of wait time. I'm assuming it used
ssh as the hosts in question have a configuration problem with their power management and
cannot be reset currently by the PDU. But it was still an odd occurrence given that the
engine host itself was the cause of the storage "outage."
Is this the correct behavior of oVirt?
-Patrick Hibbs
On 11/30/22 07:45, Murilo Morais wrote:
Konstantin, thank you very much for the explanation, it was very enlightening.
I believe I left something open in the previous message.
I'm using Hosted Engine, all VMs have HA enabled and Power Management is disabled on
all hosts. No IPMI configured (at least I didn't configure anything about iLO/IPMI in
oVirt).
There was a loss of communication with the Storage for approximately 3 minutes and this
caused all Hosts to reboot.
Em qua., 30 de nov. de 2022 às 08:50, Volenbovskyi, Konstantin
<Konstantin.Volenbovskyi@haufe.com<mailto:Konstantin.Volenbovskyi@haufe.com>>
escreveu:
Hi,
I would say that you observed ‘fencing’ and not SSH soft fencing, but actual reboot via
IPMI.
https://www.ovirt.org/develop/developer-guide/engine/automatic-fencing.html
You can disable Power management for hosts.
Before doing that you need to understand following:
-what is impact on VMs when this happens?
-the working assumption is that your VMs work just fine,
but you need to think about other cases where VMs lose their storage and/or network.
For me it seems that this was storage domain that is not a VM storage domain, so VMs’
disks were just fine.
Maybe it was hosted_storage domain in your case…
-any of those VMs are High-availability VMs? Once you disable Power
Management you will not have automatic restart on different hosts of those.
You need to understand that idea of fencing is either to recover host automatically and
possibly to restart VMs
and make sure that there are no duplicated VMs.
There are 100% cases where fencing is used and there is subset of those, X% number of
cases where you would consider that behavior is suboptimal.
The drawback of disabling fencing is that you might get suboptimal behavior in Y% cases
(100% minus X%)
BR,
Konstantin
From: Murilo Morais <murilo@evocorp.com.br<mailto:murilo@evocorp.com.br>>
Date: Wednesday, 30 November 2022 at 12:13
To: users <users@ovirt.org<mailto:users@ovirt.org>>
Subject: [ovirt-users] Forced restart when losing communication with the Storages
Good morning everyone!
Is there a way to disable the forced reboot of the machines? This morning there was an
event in our infrastructure where the hosts lost communication with the Storage but this
caused all the hosts to restart abruptly.
Would this be the correct behavior of oVirt? Is there any way to disable this?
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