Hi All,
What happens to a running qemu-kvm virtual machine when the host shuts down or reboots?
Does the hypervisor issue a shutdown to the VM? Or freeze and save the vm? Or just cut the vm's leg off?
Many thanks, -T
On 3/28/25 2:41 PM, ToddAndMargo via users wrote:
What happens to a running qemu-kvm virtual machine when the host shuts down or reboots?
Does the hypervisor issue a shutdown to the VM? Or freeze and save the vm? Or just cut the vm's leg off?
It should freeze it and restore at boot. You should see messages about that in the logs.
On 3/28/25 4:49 PM, Samuel Sieb wrote:
On 3/28/25 2:41 PM, ToddAndMargo via users wrote:
What happens to a running qemu-kvm virtual machine when the host shuts down or reboots?
Does the hypervisor issue a shutdown to the VM? Or freeze and save the vm? Or just cut the vm's leg off?
It should freeze it and restore at boot. You should see messages about that in the logs.
Is this configurable?
ToddAndMargo via users wrote:
On 3/28/25 4:49 PM, Samuel Sieb wrote:
On 3/28/25 2:41 PM, ToddAndMargo via users wrote:
What happens to a running qemu-kvm virtual machine when the host shuts down or reboots?
Does the hypervisor issue a shutdown to the VM? Or freeze and save the vm? Or just cut the vm's leg off?
It should freeze it and restore at boot. You should see messages about that in the logs.
Is this configurable?
It is handled by the libvirt-guest service, which is not enabled by default.
$ systemctl status libvirt-guests.service ○ libvirt-guests.service - libvirt guests suspend/resume service Loaded: loaded (/usr/lib/systemd/system/libvirt-guests.service; disabled; preset: disabled) Drop-In: /usr/lib/systemd/system/service.d └─10-timeout-abort.conf Active: inactive (dead) Docs: man:libvirt-guests(8) https://libvirt.org/
The referenced man page lists the various options which may be configured, whether to suspend (the default) or shutdown the guests, how long to wait, etc.
On 3/28/25 7:39 PM, Todd Zullinger wrote:
ToddAndMargo via users wrote:
On 3/28/25 4:49 PM, Samuel Sieb wrote:
On 3/28/25 2:41 PM, ToddAndMargo via users wrote:
What happens to a running qemu-kvm virtual machine when the host shuts down or reboots?
Does the hypervisor issue a shutdown to the VM? Or freeze and save the vm? Or just cut the vm's leg off?
It should freeze it and restore at boot. You should see messages about that in the logs.
Is this configurable?
It is handled by the libvirt-guest service, which is not enabled by default.
$ systemctl status libvirt-guests.service ○ libvirt-guests.service - libvirt guests suspend/resume service Loaded: loaded (/usr/lib/systemd/system/libvirt-guests.service; disabled; preset: disabled) Drop-In: /usr/lib/systemd/system/service.d └─10-timeout-abort.conf Active: inactive (dead) Docs: man:libvirt-guests(8) https://libvirt.org/
The referenced man page lists the various options which may be configured, whether to suspend (the default) or shutdown the guests, how long to wait, etc.
Thank you!
On 3/28/25 7:39 PM, Todd Zullinger wrote:
ToddAndMargo via users wrote:
On 3/28/25 4:49 PM, Samuel Sieb wrote:
On 3/28/25 2:41 PM, ToddAndMargo via users wrote:
What happens to a running qemu-kvm virtual machine when the host shuts down or reboots?
Does the hypervisor issue a shutdown to the VM? Or freeze and save the vm? Or just cut the vm's leg off?
It should freeze it and restore at boot. You should see messages about that in the logs.
Is this configurable?
It is handled by the libvirt-guest service, which is not enabled by default.
$ systemctl status libvirt-guests.service ○ libvirt-guests.service - libvirt guests suspend/resume service Loaded: loaded (/usr/lib/systemd/system/libvirt-guests.service; disabled; preset: disabled) Drop-In: /usr/lib/systemd/system/service.d └─10-timeout-abort.conf Active: inactive (dead) Docs: man:libvirt-guests(8) https://libvirt.org/
The referenced man page lists the various options which may be configured, whether to suspend (the default) or shutdown the guests, how long to wait, etc.
Hmmmm.....
$ ls -al /etc/sysconfig/libvirt-guests ls: cannot access '/etc/sysconfig/libvirt-guests': No such file or directory
$ systemctl status libvirt-guests.service ○ libvirt-guests.service - libvirt guests suspend/resume service Loaded: loaded (/usr/lib/systemd/system/libvirt-guests.service; disabled; > Drop-In: /usr/lib/systemd/system/service.d └─10-timeout-abort.conf, 50-keep-warm.conf Active: inactive (dead) Docs: man:libvirt-guests(8) https://libvirt.org/
On 3/28/25 8:01 PM, ToddAndMargo via users wrote:
On 3/28/25 7:39 PM, Todd Zullinger wrote:
It is handled by the libvirt-guest service, which is not enabled by default.
$ systemctl status libvirt-guests.service ○ libvirt-guests.service - libvirt guests suspend/resume service Loaded: loaded (/usr/lib/systemd/system/libvirt-guests.service; disabled; preset: disabled) Drop-In: /usr/lib/systemd/system/service.d └─10-timeout-abort.conf Active: inactive (dead) Docs: man:libvirt-guests(8) https://libvirt.org/
The referenced man page lists the various options which may be configured, whether to suspend (the default) or shutdown the guests, how long to wait, etc.
$ ls -al /etc/sysconfig/libvirt-guests ls: cannot access '/etc/sysconfig/libvirt-guests': No such file or directory
It only exists if you create it.
$ systemctl status libvirt-guests.service ○ libvirt-guests.service - libvirt guests suspend/resume service Loaded: loaded (/usr/lib/systemd/system/libvirt-guests.service; disabled; > Drop-In: /usr/lib/systemd/system/service.d └─10-timeout-abort.conf, 50-keep-warm.conf Active: inactive (dead) Docs: man:libvirt-guests(8) https://libvirt.org/
You need to enable the service, then it will suspend guests at shutdown by default. It's been a very long time since I configured these things, so I forgot about this step.
On 3/28/25 2:41 PM, ToddAndMargo via users wrote:
Hi All,
What happens to a running qemu-kvm virtual machine when the host shuts down or reboots?
Does the hypervisor issue a shutdown to the VM? Or freeze and save the vm? Or just cut the vm's leg off?
Many thanks, -T
Oh holy Poop!
The default from, the XML file is <on_poweroff>destroy</on_poweroff>
And virt-manager won't let your change it.
Referencing
https://docs.redhat.com/en/documentation/red_hat_enterprise_linux/6/html/vir...
The options are:
destroy restart preserve (which is really destroy but keep a record) rename-restart
Our friendly AI over on search.brave.com says I have the option of <on_shutdown>shutdown</on_shutdown> But it is not the case.
So hopefully Sam rommendation will work.
-T
On 3/29/25 1:19 AM, ToddAndMargo via users wrote:
On 3/28/25 2:41 PM, ToddAndMargo via users wrote:
Hi All,
What happens to a running qemu-kvm virtual machine when the host shuts down or reboots?
Does the hypervisor issue a shutdown to the VM? Or freeze and save the vm? Or just cut the vm's leg off?
Many thanks, -T
Oh holy Poop!
The default from, the XML file is <on_poweroff>destroy</on_poweroff>
And virt-manager won't let your change it.
Referencing
https://docs.redhat.com/en/documentation/red_hat_enterprise_linux/6/ html/virtualization_administration_guide/sect-libvirt-dom-xml-event- config#sect-libvirt-dom-xml-event-config
The options are:
destroy restart preserve (which is really destroy but keep a record) rename-restart
Our friendly AI over on search.brave.com says I have the option of <on_shutdown>shutdown</on_shutdown> But it is not the case.
So hopefully Sam rommendation will work.
-T
Sam's and Todd's suggestions worked.
I started a virtual machine that has autologin configured (lxdm), logged out to the lxdm greeter, then shutdown the host.
After reboot eh host, the VM had autologged it, meaning it had started from scratch. Had it been a suspend, I would have been at the greeter.
Thank you!
-
Samuel Sieb -
Todd Zullinger -
ToddAndMargo