Pause QEMU/KVM VM (save RAM and CPU state to disk) like vmware Player?

Question

Is it possible to save the state of a virtual machine under QEMU/KVM/libvirt (on x86-64) to disk like you can on vmware Player, that means:

• The RAM and CPU/system state is save to disk
• The OS is stopped from the outside (no suspend to disk within the VM)
• The VM can be continued after rebooting the host?

If it is possible, would it need special drivers within the VM? Which one for Linux and Windows 7 guests?

Solution 1

The virt-manager window has a feature "shut down" -> "save".

Additional drivers are not required. I think the obvious bad thing happens with system time inside the guest. I don't know if there are guest drivers available to let the clock catch up.

Solution 2

To achieve the same thing as VMmware's "Suspend" in virsh, do:

virsh managedsave <domain-name>

The machine can later be resumed with

virsh start <domain-name>

On my tested host (Ubuntu Server 14.04), the save file is stored at:

/var/lib/libvirt/qemu/save/<domain-name>.save

Solution 3

The Red Hat Virtualization Deployment and Administration Guide has a section on this, but if you don't have access then it wont be much help...

In a nutshell, what you are looking for is the virsh dompmsuspend command and option. The GUI utilities for KVM are okay but leave a LOT of functionality out. The virsh command can do anything you need it to, given the right options and parameters. I am not familiar with 'suspending' a KVM guest, so I can't really give you much guidance, but the documentation should have everything you need.

Comments

[Admin]

virsh knows the commands suspend, dompmsuspend and managedsave for different tasks (see access.redhat.com/documentation/en-US/Red_Hat_Enterprise_Lin‌​ux/…)

[Admin]

specifically managedsave is the one which meets these requirements

[Admin]

I am new to qemu, but doesn't savevm do what you want?

[Ned64]

So it has. Thanks very much, had not spotted it. For everyone who is interested, this needs space in /home/$USER/.config/libvirt/qemu/save which may be a link to a folder on a larger disk if needed.

[Ned64]

Thanks for the reply! That's what @ridgy suggested (and @sourcejedi detailed in its comment). Used virt-manager for the moment but shall try this out in the beloved command line, as well.

[Ned64]

Thanks, this is the command line equivalent of the accepted answer and useful as an addition.