Shutdown guests on powerfailure version II

ThomasRonshof · 02-09-2012, 06:16 AM

Hi,

Running on Cent OS 6.2, using KVM.

When the power fails, the nut (ups software) initiates a shutdown on the host after a couple of minutes.
The shutdown command runs a /etc/rc.d/rc0.d/K01libvirt-guests, which do a virsh save on all active guests.

If having several guests running, this can take some time, 10-20 minutes, resulting the batteri may run out of power, and the systems are forced off, together with the guests.

How to solve this ?

I want the shutdown command on the host to shutdown the guests instead of saving their states. Is that possible in a good way, instead of changing the K01libvirt-guests script ?

Regards.

jefro · 02-10-2012, 03:13 PM

Pretty sure the guests ought to be handled by acpi or apm I'd think. Might have to write a script that ssh's to them to do a shutdown.

ThomasRonshof · 02-11-2012, 02:46 AM

Good idea !

I already do a ssh to them, to inform of powerfailure with a wall-command.

Must just find where to put that script...

catkin · 02-11-2012, 03:46 AM

Assuming you ssh into the guests as root to run wall, how about running a shutdown command afterwards, something like shutdown -h +1

ThomasRonshof · 02-11-2012, 04:04 AM

Well, I will consider that... just not sure, if it's too soon to initiate a shutdown after the first wall-notice after powerfailure. If power comes back after 30 seconds, there's no need to do a shutdown... but maybe I can adjust the warning to come after 1 minute instead and do both at the same time...

catkin · 02-11-2012, 04:24 AM

Or maybe ...

Run wall on power loss to give maximum time for users to save their work.
Wait a while.
If power comes back during the while, run wall again to inform the users it's OK now.
If power has not come back during the while, run the shutdown command (which also sends a message to all users).

Are all your users terminal users? If not, something like dialog/yad/zenity would be required to message the GUI users.

ThomasRonshof · 02-11-2012, 04:46 AM

Thanks.

I need to look at the nut software, to see how to do that.

Yes, we also have some GUI users running Gnome. How do i send messages to the Gnome desktop ?

catkin · 02-11-2012, 05:28 AM

Quote:

Originally Posted by ThomasRonshof

Yes, we also have some GUI users running Gnome. How do i send messages to the Gnome desktop ?

I can't answer that completely but can give some pointers.

The user needs to give permission for other users on the local host to write to their X display. Assuming they are bash users this can be done either globally in /etc/profile or per-user in ~/.bash_profile files by including

Code:

[[ $DISPLAY ]] && /usr/bin/xhost +localhost

To write to all users you would need to enumerate all the X displays on the computer. I don't know how to do that.

The displays look something like localhost:0.0

You would have to loop over each of the X displays and, if using yad, run code something like

Code:

export LANG=C
export DISPLAY='localhost:0.0'
yad --button='OK:0' --on-top --sticky --title=" <your chosen title> " --text "<your chosen text>"

You could prettify it by adding --image <path/to/icon/file> and --window-icon <path/to/another/icon/file>. One appears in the title bar and the other in the text area.

ThomasRonshof · 02-11-2012, 06:04 AM

Thanks :-)

I will look into that.

jefro · 02-11-2012, 01:12 PM

In the deal maybe dialog or xdialog or such in a popup.