Hi,
Today, I started testing on my Ovirt 3.1 installation (from dreyou
repos) running on 3 x Centos 6.3 hypervisors the High Availability
features and the fence mechanism.
As yesterday, I have reported in a previous email thread, that the
migration priority queue cannot be increased (bug) in this current
version, I decided to test what the official documentation says about
the High Availability cases.
This will be a disaster case scenarios to suffer from if one hypervisor
has a power outage/hardware problem and the VMs running on it are not
migrating on other spare resources.
In the official documenation from ovirt.org it is quoted the following:
/High availability /
//
/Allows critical VMs to be restarted on another host in the event of
hardware failure with three levels of priority, taking into account
resiliency policy. /
//
* /Resiliency policy to control high availability VMs at the cluster
level. /
* /Supports application-level high availability with supported fencing
agents. /
As well as in the Architecture description:
/High Availability - restart guest VMs from failed hosts automatically
on other hosts/
So the testing went like this -- One VM running a linux box, having the
check box "High Available" and "Priority for Run/Migration queue:" set
to Low. On Host we have the check box to "Any Host in Cluster", without
"Allow VM migration only upon Admin specific request" checked.
My environment:
Configuration : 2 x Hypervisors (same cluster/hardware configuration) ;
1 x Hypervisor + acting as a NAS (NFS) server (different
cluster/hardware configuration)
Actions: Went and cut-off the power from one of the hypervisors from the
2 node clusters, while the VM was running on. This would translate to a
power outage.
Results: The hypervisor node that suffered from the outage is showing in
Hosts tab as Non Responsive on Status, and the VM has a question mark
and cannot be powered off or nothing (therefore it's stuck).
In the Log console in GUI, I get:
Host Hyper01 is non-responsive.
VM Web-Frontend01 was set to the Unknown status.
There is nothing I could I could do besides clicking on the Hyper01
"Confirm Host as been rebooted", afterwards the VM starts on the Hyper02
with a cold reboot of the VM.
The Log console changes to:
Vm Web-Frontend01 was shut down due to Hyper01 host reboot or manual fence
All VMs' status on Non-Responsive Host Hyper01 were changed to 'Down' by
admin@internal
Manual fencing for host Hyper01 was started.
VM Web-Frontend01 was restarted on Host Hyper02
I would like you approach on this problem, reading the documentation &
features pages on the official website, I suppose that this would have
been an automatically mechanism working on some sort of a vdsm & engine
fencing action. Am I missing something regarding it ?
Thank you for your patience reading this.
Regards,
Alex.
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